Nr sidelink intra-cell relay measurement

ABSTRACT

Method and apparatus for configuring a UE with a relay measurement configuration for measuring one or more candidate relays in preparation of switching to a target relay. The apparatus receives, from a source relay, a candidate relay configuration. The candidate relay configuration including information of candidate relays and a relay measurement configuration. The apparatus measures a reference signal of the source relay and each of the candidate relays based on the candidate relay configuration. The apparatus transmits, to the source relay, a measurement report of the reference signal of the subset of candidate relays. The apparatus establishes a connection with a subset of candidate relays. The apparatus receives, from the source relay, a relay switch command to switch to a target relay from the subset of candidate relays.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of and priority to U.S. ProvisionalApplication Ser. No. 63/075,434, entitled “NR Sidelink Intra-Cell RelayMeasurement” and filed on Sep. 8, 2020, which is expressly incorporatedby reference herein in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to communication systems, andmore particularly, to a configuration for sidelink intra-cell relaymeasurement.

INTRODUCTION

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources. Examples of suchmultiple-access technologies include code division multiple access(CDMA) systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, orthogonal frequency divisionmultiple access (OFDMA) systems, single-carrier frequency divisionmultiple access (SC-FDMA) systems, and time division synchronous codedivision multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example telecommunication standardis 5G New Radio (NR). 5G NR is part of a continuous mobile broadbandevolution promulgated by Third Generation Partnership Project (3GPP) tomeet new requirements associated with latency, reliability, security,scalability (e.g., with Internet of Things (IoT)), and otherrequirements. 5G NR includes services associated with enhanced mobilebroadband (eMBB), massive machine type communications (mMTC), andultra-reliable low latency communications (URLLC). Some aspects of 5G NRmay be based on the 4G Long Term Evolution (LTE) standard. There existsa need for further improvements in 5G NR technology. These improvementsmay also be applicable to other multi-access technologies and thetelecommunication standards that employ these technologies.

BRIEF SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

In an aspect of the disclosure, a method, a computer-readable medium,and an apparatus are provided. The apparatus may be a device at a userequipment (UE). The device may be a processor and/or a modem at a UE orthe UE itself. The apparatus receives, from a source relay, a candidaterelay configuration, the candidate relay configuration includinginformation of candidate relays and a relay measurement configuration.The apparatus measures a reference signal of the source relay and eachof the candidate relays based on the candidate relay configuration. Theapparatus transmits, to the source relay, a measurement report of thereference signal of the subset of candidate relays. The apparatusestablishes a connection with a subset of candidate relays. Theapparatus receives, from the source relay, a relay switch command toswitch to a target relay from the subset of candidate relays.

In an aspect of the disclosure, a method, a computer-readable medium,and an apparatus are provided. The apparatus may be a device at a UE ora base station. The device may be a processor and/or a modem at a UE orbase station or the UE or base station itself. The apparatustransmitting, to a UE, a candidate relay configuration, the candidaterelay configuration including information of candidate relays and arelay measurement configuration. The apparatus receives, from the UE, ameasurement report of a subset of candidate relays. The apparatustransmits, to the UE, a relay switch command to switch to a target relayfrom the subset of candidate relays.

In an aspect of the disclosure, a method, a computer-readable medium,and an apparatus are provided. The apparatus may be a device at a basestation. The device may be a processor and/or a modem at a base stationor the base station itself. The apparatus configures a candidate relayconfiguration including information of candidate relays and a relaymeasurement configuration. The apparatus transmits, to a source relay,the candidate relay configuration. The apparatus receives, from thesource relay, a measurement report of reference signals of a subset ofcandidate relays. The apparatus selects a target relay from the subsetof candidate relays based on the measurement report. The apparatustransmits, to the source relay, a relay switch command for a UE toswitch to the target relay.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network.

FIG. 2A is a diagram illustrating an example of a first frame, inaccordance with various aspects of the present disclosure.

FIG. 2B is a diagram illustrating an example of DL channels within asubframe, in accordance with various aspects of the present disclosure.

FIG. 2C is a diagram illustrating an example of a second frame, inaccordance with various aspects of the present disclosure.

FIG. 2D is a diagram illustrating an example of UL channels within asubframe, in accordance with various aspects of the present disclosure.

FIG. 3 is a diagram illustrating an example of a base station and userequipment (UE) in an access network.

FIG. 4 illustrates an example of relay switching in a wirelesscommunication system.

FIG. 5 illustrates an example of radio link failure of a relay device.

FIGS. 6A-6B illustrate examples of a relay measurement configuration.

FIG. 7 is a call flow diagram of signaling between a UE, a relay device,and a base station.

FIG. 8 is a flowchart of a method of wireless communication.

FIG. 9 is a flowchart of a method of wireless communication.

FIG. 10 is a diagram illustrating an example of a hardwareimplementation for an example apparatus.

FIG. 11 is a flowchart of a method of wireless communication.

FIG. 12 is a flowchart of a method of wireless communication.

FIG. 13 is a diagram illustrating an example of a hardwareimplementation for an example apparatus.

FIG. 14 is a flowchart of a method of wireless communication.

FIG. 15 is a diagram illustrating an example of a hardwareimplementation for an example apparatus.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented withreference to various apparatus and methods. These apparatus and methodswill be described in the following detailed description and illustratedin the accompanying drawings by various blocks, components, circuits,processes, algorithms, etc. (collectively referred to as “elements”).These elements may be implemented using electronic hardware, computersoftware, or any combination thereof. Whether such elements areimplemented as hardware or software depends upon the particularapplication and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or anycombination of elements may be implemented as a “processing system” thatincludes one or more processors. Examples of processors includemicroprocessors, microcontrollers, graphics processing units (GPUs),central processing units (CPUs), application processors, digital signalprocessors (DSPs), reduced instruction set computing (RISC) processors,systems on a chip (SoC), baseband processors, field programmable gatearrays (FPGAs), programmable logic devices (PLDs), state machines, gatedlogic, discrete hardware circuits, and other suitable hardwareconfigured to perform the various functionality described throughoutthis disclosure. One or more processors in the processing system mayexecute software. Software shall be construed broadly to meaninstructions, instruction sets, code, code segments, program code,programs, subprograms, software components, applications, softwareapplications, software packages, routines, subroutines, objects,executables, threads of execution, procedures, functions, etc., whetherreferred to as software, firmware, middleware, microcode, hardwaredescription language, or otherwise.

Accordingly, in one or more example embodiments, the functions describedmay be implemented in hardware, software, or any combination thereof. Ifimplemented in software, the functions may be stored on or encoded asone or more instructions or code on a computer-readable medium.Computer-readable media includes computer storage media. Storage mediamay be any available media that can be accessed by a computer. By way ofexample, and not limitation, such computer-readable media can comprise arandom-access memory (RAM), a read-only memory (ROM), an electricallyerasable programmable ROM (EEPROM), optical disk storage, magnetic diskstorage, other magnetic storage devices, combinations of the types ofcomputer-readable media, or any other medium that can be used to storecomputer executable code in the form of instructions or data structuresthat can be accessed by a computer.

While aspects and implementations are described in this application byillustration to some examples, those skilled in the art will understandthat additional implementations and use cases may come about in manydifferent arrangements and scenarios. Innovations described herein maybe implemented across many differing platform types, devices, systems,shapes, sizes, and packaging arrangements. For example, implementationsand/or uses may come about via integrated chip implementations and othernon-module-component based devices (e.g., end-user devices, vehicles,communication devices, computing devices, industrial equipment,retail/purchasing devices, medical devices, artificial intelligence(AI)-enabled devices, etc.). While some examples may or may not bespecifically directed to use cases or applications, a wide assortment ofapplicability of described innovations may occur. Implementations mayrange a spectrum from chip-level or modular components to non-modular,non-chip-level implementations and further to aggregate, distributed, ororiginal equipment manufacturer (OEM) devices or systems incorporatingone or more aspects of the described innovations. In some practicalsettings, devices incorporating described aspects and features may alsoinclude additional components and features for implementation andpractice of claimed and described aspect. For example, transmission andreception of wireless signals necessarily includes a number ofcomponents for analog and digital purposes (e.g., hardware componentsincluding antenna, RF-chains, power amplifiers, modulators, buffer,processor(s), interleaver, adders/summers, etc.). It is intended thatinnovations described herein may be practiced in a wide variety ofdevices, chip-level components, systems, distributed arrangements,aggregated or disaggregated components, end-user devices, etc. ofvarying sizes, shapes, and constitution.

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network 100. The wireless communications system(also referred to as a wireless wide area network (WWAN)) includes basestations 102, UEs 104, an Evolved Packet Core (EPC) 160, and anothercore network 190 (e.g., a 5G Core (5 GC)). The base stations 102 mayinclude macrocells (high power cellular base station) and/or small cells(low power cellular base station). The macrocells include base stations.The small cells include femtocells, picocells, and microcells.

The base stations 102 configured for 4G LTE (collectively referred to asEvolved Universal Mobile Telecommunications System (UMTS) TerrestrialRadio Access Network (E-UTRAN)) may interface with the EPC 160 throughfirst backhaul links 132 (e.g., S1 interface). The base stations 102configured for 5G NR (collectively referred to as Next Generation RAN(NG-RAN)) may interface with core network 190 through second backhaullinks 184. In addition to other functions, the base stations 102 mayperform one or more of the following functions: transfer of user data,radio channel ciphering and deciphering, integrity protection, headercompression, mobility control functions (e.g., handover, dualconnectivity), inter-cell interference coordination, connection setupand release, load balancing, distribution for non-access stratum (NAS)messages, NAS node selection, synchronization, radio access network(RAN) sharing, multimedia broadcast multicast service (MBMS), subscriberand equipment trace, RAN information management (RIM), paging,positioning, and delivery of warning messages. The base stations 102 maycommunicate directly or indirectly (e.g., through the EPC 160 or corenetwork 190) with each other over third backhaul links 134 (e.g., X2interface). The first backhaul links 132, the second backhaul links 184,and the third backhaul links 134 may be wired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Eachof the base stations 102 may provide communication coverage for arespective geographic coverage area 110. There may be overlappinggeographic coverage areas 110. For example, the small cell 102′ may havea coverage area 110′ that overlaps the coverage area 110 of one or moremacro base stations 102. A network that includes both small cell andmacrocells may be known as a heterogeneous network. A heterogeneousnetwork may also include Home Evolved Node Bs (eNBs) (HeNBs), which mayprovide service to a restricted group known as a closed subscriber group(CSG). The communication links 120 between the base stations 102 and theUEs 104 may include uplink (UL) (also referred to as reverse link)transmissions from a UE 104 to a base station 102 and/or downlink (DL)(also referred to as forward link) transmissions from a base station 102to a UE 104. The communication links 120 may use multiple-input andmultiple-output (MIMO) antenna technology, including spatialmultiplexing, beamforming, and/or transmit diversity. The communicationlinks may be through one or more carriers. The base stations 102/UEs 104may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz)bandwidth per carrier allocated in a carrier aggregation of up to atotal of Yx MHz (x component carriers) used for transmission in eachdirection. The carriers may or may not be adjacent to each other.Allocation of carriers may be asymmetric with respect to DL and UL(e.g., more or fewer carriers may be allocated for DL than for UL). Thecomponent carriers may include a primary component carrier and one ormore secondary component carriers. A primary component carrier may bereferred to as a primary cell (PCell) and a secondary component carriermay be referred to as a secondary cell (SCell).

Certain UEs 104 may communicate with each other using device-to-device(D2D) communication link 158. The D2D communication link 158 may use theDL/UL WWAN spectrum. The D2D communication link 158 may use one or moresidelink channels, such as a physical sidelink broadcast channel(PSBCH), a physical sidelink discovery channel (PSDCH), a physicalsidelink shared channel (PSSCH), and a physical sidelink control channel(PSCCH). D2D communication may be through a variety of wireless D2Dcommunications systems, such as for example, WiMedia, Bluetooth, ZigBee,Wi-Fi based on the Institute of Electrical and Electronics Engineers(IEEE) 802.11 standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi accesspoint (AP) 150 in communication with Wi-Fi stations (STAs) 152 viacommunication links 154, e.g., in a 5 GHz unlicensed frequency spectrumor the like. When communicating in an unlicensed frequency spectrum, theSTAs 152/AP 150 may perform a clear channel assessment (CCA) prior tocommunicating in order to determine whether the channel is available.

The small cell 102′ may operate in a licensed and/or an unlicensedfrequency spectrum. When operating in an unlicensed frequency spectrum,the small cell 102′ may employ NR and use the same unlicensed frequencyspectrum (e.g., 5 GHz, or the like) as used by the Wi-Fi AP 150. Thesmall cell 102′, employing NR in an unlicensed frequency spectrum, mayboost coverage to and/or increase capacity of the access network.

The electromagnetic spectrum is often subdivided, based onfrequency/wavelength, into various classes, bands, channels, etc. In 5GNR, two initial operating bands have been identified as frequency rangedesignations FR1 (410 MHz-7.125 GHz) and FR2 (24.25 GHz-52.6 GHz).Although a portion of FR1 is greater than 6 GHz, FR1 is often referredto (interchangeably) as a “sub-6 GHz” band in various documents andarticles. A similar nomenclature issue sometimes occurs with regard toFR2, which is often referred to (interchangeably) as a “millimeter wave”band in documents and articles, despite being different from theextremely high frequency (EHF) band (30 GHz-300 GHz) which is identifiedby the International Telecommunications Union (ITU) as a “millimeterwave” band.

The frequencies between FR1 and FR2 are often referred to as mid-bandfrequencies. Recent 5G NR studies have identified an operating band forthese mid-band frequencies as frequency range designation FR3 (7.125GHz-24.25 GHz). Frequency bands falling within FR3 may inherit FR1characteristics and/or FR2 characteristics, and thus may effectivelyextend features of FR1 and/or FR2 into mid-band frequencies. Inaddition, higher frequency bands are currently being explored to extend5G NR operation beyond 52.6 GHz. For example, three higher operatingbands have been identified as frequency range designations FR4a or FR4-1(52.6 GHz-71 GHz), FR4 (52.6 GHz-114.25 GHz), and FR5 (114.25 GHz-300GHz). Each of these higher frequency bands falls within the EHF band.

With the above aspects in mind, unless specifically stated otherwise, itshould be understood that the term “sub-6 GHz” or the like if usedherein may broadly represent frequencies that may be less than 6 GHz,may be within FR1, or may include mid-band frequencies. Further, unlessspecifically stated otherwise, it should be understood that the term“millimeter wave” or the like if used herein may broadly representfrequencies that may include mid-band frequencies, may be within FR2,FR4, FR4-a or FR4-1, and/or FR5, or may be within the EHF band.

A base station 102, whether a small cell 102′ or a large cell (e.g.,macro base station), may include and/or be referred to as an eNB, gNodeB(gNB), or another type of base station. Some base stations, such as gNB180 may operate in a traditional sub 6 GHz spectrum, in millimeter wavefrequencies, and/or near millimeter wave frequencies in communicationwith the UE 104. When the gNB 180 operates in millimeter wave or nearmillimeter wave frequencies, the gNB 180 may be referred to as amillimeter wave base station. The millimeter wave base station 180 mayutilize beamforming 182 with the UE 104 to compensate for the path lossand short range. The base station 180 and the UE 104 may each include aplurality of antennas, such as antenna elements, antenna panels, and/orantenna arrays to facilitate the beamforming.

The base station 180 may transmit a beamformed signal to the UE 104 inone or more transmit directions 182′. The UE 104 may receive thebeamformed signal from the base station 180 in one or more receivedirections 182″. The UE 104 may also transmit a beamformed signal to thebase station 180 in one or more transmit directions. The base station180 may receive the beamformed signal from the UE 104 in one or morereceive directions. The base station 180/UE 104 may perform beamtraining to determine the best receive and transmit directions for eachof the base station 180/UE 104. The transmit and receive directions forthe base station 180 may or may not be the same. The transmit andreceive directions for the UE 104 may or may not be the same.

The EPC 160 may include a Mobility Management Entity (MME) 162, otherMMES 164, a Serving Gateway 166, a Multimedia Broadcast MulticastService (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC)170, and a Packet Data Network (PDN) Gateway 172. The MME 162 may be incommunication with a Home Subscriber Server (HSS) 174. The MME 162 isthe control node that processes the signaling between the UEs 104 andthe EPC 160. Generally, the MME 162 provides bearer and connectionmanagement. All user Internet protocol (IP) packets are transferredthrough the Serving Gateway 166, which itself is connected to the PDNGateway 172. The PDN Gateway 172 provides UE IP address allocation aswell as other functions. The PDN Gateway 172 and the BM-SC 170 areconnected to the IP Services 176. The IP Services 176 may include theInternet, an intranet, an IP Multimedia Subsystem (IMS), a PS StreamingService, and/or other IP services. The BM-SC 170 may provide functionsfor MBMS user service provisioning and delivery. The BM-SC 170 may serveas an entry point for content provider MBMS transmission, may be used toauthorize and initiate MBMS Bearer Services within a public land mobilenetwork (PLMN), and may be used to schedule MBMS transmissions. The MBMSGateway 168 may be used to distribute MBMS traffic to the base stations102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN)area broadcasting a particular service, and may be responsible forsession management (start/stop) and for collecting eMBMS relatedcharging information.

The core network 190 may include an Access and Mobility ManagementFunction (AMF) 192, other AMFs 193, a Session Management Function (SMF)194, and a User Plane Function (UPF) 195. The AMF 192 may be incommunication with a Unified Data Management (UDM) 196. The AMF 192 isthe control node that processes the signaling between the UEs 104 andthe core network 190. Generally, the AMF 192 provides QoS flow andsession management. All user Internet protocol (IP) packets aretransferred through the UPF 195. The UPF 195 provides UE IP addressallocation as well as other functions. The UPF 195 is connected to theIP Services 197. The IP Services 197 may include the Internet, anintranet, an IP Multimedia Subsystem (IMS), a Packet Switch (PS)Streaming (PSS) Service, and/or other IP services.

The base station may include and/or be referred to as a gNB, Node B,eNB, an access point, a base transceiver station, a radio base station,a radio transceiver, a transceiver function, a basic service set (BSS),an extended service set (ESS), a transmit reception point (TRP), or someother suitable terminology. The base station 102 provides an accesspoint to the EPC 160 or core network 190 for a UE 104. Examples of UEs104 include a cellular phone, a smart phone, a session initiationprotocol (SIP) phone, a laptop, a personal digital assistant (PDA), asatellite radio, a global positioning system, a multimedia device, avideo device, a digital audio player (e.g., MP3 player), a camera, agame console, a tablet, a smart device, a wearable device, a vehicle, anelectric meter, a gas pump, a large or small kitchen appliance, ahealthcare device, an implant, a sensor/actuator, a display, or anyother similar functioning device. Some of the UEs 104 may be referred toas IoT devices (e.g., parking meter, gas pump, toaster, vehicles, heartmonitor, etc.). The UE 104 may also be referred to as a station, amobile station, a subscriber station, a mobile unit, a subscriber unit,a wireless unit, a remote unit, a mobile device, a wireless device, awireless communications device, a remote device, a mobile subscriberstation, an access terminal, a mobile terminal, a wireless terminal, aremote terminal, a handset, a user agent, a mobile client, a client, orsome other suitable terminology. In some scenarios, the term UE may alsoapply to one or more companion devices such as in a device constellationarrangement. One or more of these devices may collectively access thenetwork and/or individually access the network.

Referring again to FIG. 1, in certain aspects, the UE 104 may beconfigured to perform measurement of one or more candidate relays inpreparation of switching to a target relay. For example, the UE 104 maycomprise a candidate relay component 198 configured to receive acandidate relay configuration having at least a relay measurementconfiguration. The UE 104 may receive, from a source relay, a candidaterelay configuration, the candidate relay configuration includinginformation of candidate relays and a relay measurement configuration.The UE 104 may measure a reference signal of the source relay and eachof the candidate relays based on the candidate relay configuration. TheUE 104 may transmit, to the source relay, a measurement report of thereference signal of the subset of candidate relays. The UE 104 mayestablish a connection with a subset of candidate relays. The UE 104 mayreceive, from the source relay, a relay switch command to switch to atarget relay from the subset of candidate relays.

Referring again to FIG. 1, in certain aspects, the source relay (e.g.,UE 104 or base station 102/180) may be configured to transmit acandidate relay configuration including at least a relay measurementconfiguration. For example, the source relay may comprise a candidaterelay component (e.g., 198 or 199) configured to transmit the candidaterelay configuration including at least the relay measurementconfiguration to a UE 104. The source relay may transmit, to a UE 104, acandidate relay configuration, the candidate relay configurationincluding information of candidate relays and a relay measurementconfiguration. The source relay may receive, from the UE 104, ameasurement report of a subset of candidate relays. The source relay maytransmit, to the UE 104, a relay switch command to switch to a targetrelay from the subset of candidate relays.

Referring again to FIG. 1, in certain aspects, the base station 180 maybe configured to configure a candidate relay configuration including atleast a relay measurement configuration. For example, the base station180 may comprise a candidate relay component 199 configured to transmitthe candidate relay configuration to a source relay. The base station180 may configure a candidate relay configuration including informationof candidate relays and a relay measurement configuration. The basestation 180 may transmit, to a source relay, the candidate relayconfiguration. The base station 180 may receive, from the source relay,a measurement report of reference signals of a subset of candidaterelays. The base station 180 may select a target relay from the subsetof candidate relays based on the measurement report. The base station180 may transmit, to the source relay, a relay switch command for a UEto switch to the target relay.

Although the following description may be focused on 5G NR, the conceptsdescribed herein may be applicable to other similar areas, such as LTE,LTE-A, CDMA, GSM, and other wireless technologies.

FIG. 2A is a diagram 200 illustrating an example of a first subframewithin a 5G NR frame structure. FIG. 2B is a diagram 230 illustrating anexample of DL channels within a 5G NR subframe. FIG. 2C is a diagram 250illustrating an example of a second subframe within a 5G NR framestructure. FIG. 2D is a diagram 280 illustrating an example of ULchannels within a 5G NR subframe. The 5G NR frame structure may befrequency division duplexed (FDD) in which for a particular set ofsubcarriers (carrier system bandwidth), subframes within the set ofsubcarriers are dedicated for either DL or UL, or may be time divisionduplexed (TDD) in which for a particular set of subcarriers (carriersystem bandwidth), subframes within the set of subcarriers are dedicatedfor both DL and UL. In the examples provided by FIGS. 2A, 2C, the 5G NRframe structure is assumed to be TDD, with subframe 4 being configuredwith slot format 28 (with mostly DL), where D is DL, U is UL, and F isflexible for use between DL/UL, and subframe 3 being configured withslot format 1 (with all UL). While subframes 3, 4 are shown with slotformats 1, 28, respectively, any particular subframe may be configuredwith any of the various available slot formats 0-61. Slot formats 0, 1are all DL, UL, respectively. Other slot formats 2-61 include a mix ofDL, UL, and flexible symbols. UEs are configured with the slot format(dynamically through DL control information (DCI), orsemi-statically/statically through radio resource control (RRC)signaling) through a received slot format indicator (SFI). Note that thedescription infra applies also to a 5G NR frame structure that is TDD.

FIGS. 2A-2D illustrate a frame structure, and the aspects of the presentdisclosure may be applicable to other wireless communicationtechnologies, which may have a different frame structure and/ordifferent channels. A frame (10 ms) may be divided into 10 equally sizedsubframes (1 ms). Each subframe may include one or more time slots.Subframes may also include mini-slots, which may include 7, 4, or 2symbols. Each slot may include 14 or 12 symbols, depending on whetherthe cyclic prefix (CP) is normal or extended. For normal CP, each slotmay include 14 symbols, and for extended CP, each slot may include 12symbols. The symbols on DL may be CP orthogonal frequency divisionmultiplexing (OFDM) (CP-OFDM) symbols. The symbols on UL may be CP-OFDMsymbols (for high throughput scenarios) or discrete Fourier transform(DFT) spread OFDM (DFT-s-OFDM) symbols (also referred to as singlecarrier frequency-division multiple access (SC-FDMA) symbols) (for powerlimited scenarios; limited to a single stream transmission). The numberof slots within a subframe is based on the CP and the numerology. Thenumerology defines the subcarrier spacing (SC S) and, effectively, thesymbol length/duration, which is equal to 1/SCS.

SCS μ Δf = 2^(μ) · 15 [kHz] Cyclic prefix 0 15 Normal 1 30 Normal 2 60Normal, Extended 3 120 Normal 4 240 Normal

For normal CP (14 symbols/slot), different numerologies μ 0 to 4 allowfor 1, 2, 4, 8, and 16 slots, respectively, per subframe. For extendedCP, the numerology 2 allows for 4 slots per subframe. Accordingly, fornormal CP and numerology μ, there are 14 symbols/slot and 2^(u)slots/subframe. The subcarrier spacing may be equal to 2^(u)*15 kHz,where μ is the numerology 0 to 4. As such, the numerology μ=0 has asubcarrier spacing of 15 kHz and the numerology μ=4 has a subcarrierspacing of 240 kHz. The symbol length/duration is inversely related tothe subcarrier spacing. FIGS. 2A-2D provide an example of normal CP with14 symbols per slot and numerology μ=2 with 4 slots per subframe. Theslot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and thesymbol duration is approximately 16.67 μs. Within a set of frames, theremay be one or more different bandwidth parts (BWPs) (see FIG. 2B) thatare frequency division multiplexed. Each BWP may have a particularnumerology and CP (normal or extended).

A resource grid may be used to represent the frame structure. Each timeslot includes a resource block (RB) (also referred to as physical RBs(PRBs)) that extends 12 consecutive subcarriers. The resource grid isdivided into multiple resource elements (REs). The number of bitscarried by each RE depends on the modulation scheme.

As illustrated in FIG. 2A, some of the REs carry reference (pilot)signals (RS) for the UE. The RS may include demodulation RS (DM-RS)(indicated as R for one particular configuration, but other DM-RSconfigurations are possible) and channel state information referencesignals (CSI-RS) for channel estimation at the UE. The RS may alsoinclude beam measurement RS (BRS), beam refinement RS (BRRS), and phasetracking RS (PT-RS).

FIG. 2B illustrates an example of various DL channels within a subframeof a frame. The physical downlink control channel (PDCCH) carries DCIwithin one or more control channel elements (CCEs) (e.g., 1, 2, 4, 8, or16 CCEs), each CCE including six RE groups (REGs), each REG including 12consecutive REs in an OFDM symbol of an RB. A PDCCH within one BWP maybe referred to as a control resource set (CORESET). A UE is configuredto monitor PDCCH candidates in a PDCCH search space (e.g., common searchspace, UE-specific search space) during PDCCH monitoring occasions onthe CORESET, where the PDCCH candidates have different DCI formats anddifferent aggregation levels. Additional BWPs may be located at greaterand/or lower frequencies across the channel bandwidth. A primarysynchronization signal (PSS) may be within symbol 2 of particularsubframes of a frame. The PSS is used by a UE 104 to determinesubframe/symbol timing and a physical layer identity. A secondarysynchronization signal (SSS) may be within symbol 4 of particularsubframes of a frame. The SSS is used by a UE to determine a physicallayer cell identity group number and radio frame timing. Based on thephysical layer identity and the physical layer cell identity groupnumber, the UE can determine a physical cell identifier (PCI). Based onthe PCI, the UE can determine the locations of the DM-RS. The physicalbroadcast channel (PBCH), which carries a master information block(MIB), may be logically grouped with the PSS and SSS to form asynchronization signal (SS)/PBCH block (also referred to as SS block(SSB)). The MIB provides a number of RBs in the system bandwidth and asystem frame number (SFN). The physical downlink shared channel (PDSCH)carries user data, broadcast system information not transmitted throughthe PBCH such as system information blocks (SIBs), and paging messages.

As illustrated in FIG. 2C, some of the REs carry DM-RS (indicated as Rfor one particular configuration, but other DM-RS configurations arepossible) for channel estimation at the base station. The UE maytransmit DM-RS for the physical uplink control channel (PUCCH) and DM-RSfor the physical uplink shared channel (PUSCH). The PUSCH DM-RS may betransmitted in the first one or two symbols of the PUSCH. The PUCCHDM-RS may be transmitted in different configurations depending onwhether short or long PUCCHs are transmitted and depending on theparticular PUCCH format used. The UE may transmit sounding referencesignals (SRS). The SRS may be transmitted in the last symbol of asubframe. The SRS may have a comb structure, and a UE may transmit SRSon one of the combs. The SRS may be used by a base station for channelquality estimation to enable frequency-dependent scheduling on the UL.

FIG. 2D illustrates an example of various UL channels within a subframeof a frame. The PUCCH may be located as indicated in one configuration.The PUCCH carries uplink control information (UCI), such as schedulingrequests, a channel quality indicator (CQI), a precoding matrixindicator (PMI), a rank indicator (RI), and hybrid automatic repeatrequest (HARQ) acknowledgment (ACK) (HARQ-ACK) feedback (i.e., one ormore HARQ ACK bits indicating one or more ACK and/or negative ACK(NACK)). The PUSCH carries data, and may additionally be used to carry abuffer status report (BSR), a power headroom report (PHR), and/or UCI.

FIG. 3 is a block diagram of a base station 310 in communication with aUE 350 in an access network. In the DL, IP packets from the EPC 160 maybe provided to a controller/processor 375. The controller/processor 375implements layer 3 and layer 2 functionality. Layer 3 includes a radioresource control (RRC) layer, and layer 2 includes a service dataadaptation protocol (SDAP) layer, a packet data convergence protocol(PDCP) layer, a radio link control (RLC) layer, and a medium accesscontrol (MAC) layer. The controller/processor 375 provides RRC layerfunctionality associated with broadcasting of system information (e.g.,MIB, SIBs), RRC connection control (e.g., RRC connection paging, RRCconnection establishment, RRC connection modification, and RRCconnection release), inter radio access technology (RAT) mobility, andmeasurement configuration for UE measurement reporting; PDCP layerfunctionality associated with header compression/decompression, security(ciphering, deciphering, integrity protection, integrity verification),and handover support functions; RLC layer functionality associated withthe transfer of upper layer packet data units (PDUs), error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC servicedata units (SDUs), re-segmentation of RLC data PDUs, and reordering ofRLC data PDUs; and MAC layer functionality associated with mappingbetween logical channels and transport channels, multiplexing of MACSDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs,scheduling information reporting, error correction through HARQ,priority handling, and logical channel prioritization.

The transmit (TX) processor 316 and the receive (RX) processor 370implement layer 1 functionality associated with various signalprocessing functions. Layer 1, which includes a physical (PHY) layer,may include error detection on the transport channels, forward errorcorrection (FEC) coding/decoding of the transport channels,interleaving, rate matching, mapping onto physical channels,modulation/demodulation of physical channels, and MIMO antennaprocessing. The TX processor 316 handles mapping to signalconstellations based on various modulation schemes (e.g., binaryphase-shift keying (BPSK), quadrature phase-shift keying (QPSK),M-phase-shift keying (M-PSK), M-quadrature amplitude modulation(M-QAM)). The coded and modulated symbols may then be split intoparallel streams. Each stream may then be mapped to an OFDM subcarrier,multiplexed with a reference signal (e.g., pilot) in the time and/orfrequency domain, and then combined together using an Inverse FastFourier Transform (IFFT) to produce a physical channel carrying a timedomain OFDM symbol stream. The OFDM stream is spatially precoded toproduce multiple spatial streams. Channel estimates from a channelestimator 374 may be used to determine the coding and modulation scheme,as well as for spatial processing. The channel estimate may be derivedfrom a reference signal and/or channel condition feedback transmitted bythe UE 350. Each spatial stream may then be provided to a differentantenna 320 via a separate transmitter 318 TX. Each transmitter 318 TXmay modulate a radio frequency (RF) carrier with a respective spatialstream for transmission.

At the UE 350, each receiver 354 RX receives a signal through itsrespective antenna 352. Each receiver 354 RX recovers informationmodulated onto an RF carrier and provides the information to the receive(RX) processor 356. The TX processor 368 and the RX processor 356implement layer 1 functionality associated with various signalprocessing functions. The RX processor 356 may perform spatialprocessing on the information to recover any spatial streams destinedfor the UE 350. If multiple spatial streams are destined for the UE 350,they may be combined by the RX processor 356 into a single OFDM symbolstream. The RX processor 356 then converts the OFDM symbol stream fromthe time-domain to the frequency domain using a Fast Fourier Transform(FFT). The frequency domain signal comprises a separate OFDM symbolstream for each subcarrier of the OFDM signal. The symbols on eachsubcarrier, and the reference signal, are recovered and demodulated bydetermining the most likely signal constellation points transmitted bythe base station 310. These soft decisions may be based on channelestimates computed by the channel estimator 358. The soft decisions arethen decoded and deinterleaved to recover the data and control signalsthat were originally transmitted by the base station 310 on the physicalchannel. The data and control signals are then provided to thecontroller/processor 359, which implements layer 3 and layer 2functionality.

The controller/processor 359 can be associated with a memory 360 thatstores program codes and data. The memory 360 may be referred to as acomputer-readable medium. In the UL, the controller/processor 359provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, and control signalprocessing to recover IP packets from the EPC 160. Thecontroller/processor 359 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DLtransmission by the base station 310, the controller/processor 359provides RRC layer functionality associated with system information(e.g., MIB, SIBs) acquisition, RRC connections, and measurementreporting; PDCP layer functionality associated with headercompression/decompression, and security (ciphering, deciphering,integrity protection, integrity verification); RLC layer functionalityassociated with the transfer of upper layer PDUs, error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC SDUs,re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; andMAC layer functionality associated with mapping between logical channelsand transport channels, multiplexing of MAC SDUs onto TBs,demultiplexing of MAC SDUs from TBs, scheduling information reporting,error correction through HARQ, priority handling, and logical channelprioritization.

Channel estimates derived by a channel estimator 358 from a referencesignal or feedback transmitted by the base station 310 may be used bythe TX processor 368 to select the appropriate coding and modulationschemes, and to facilitate spatial processing. The spatial streamsgenerated by the TX processor 368 may be provided to different antenna352 via separate transmitters 354TX. Each transmitter 354TX may modulatean RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station 310 in a mannersimilar to that described in connection with the receiver function atthe UE 350. Each receiver 318RX receives a signal through its respectiveantenna 320. Each receiver 318RX recovers information modulated onto anRF carrier and provides the information to a RX processor 370.

The controller/processor 375 can be associated with a memory 376 thatstores program codes and data. The memory 376 may be referred to as acomputer-readable medium. In the UL, the controller/processor 375provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover IP packets from the UE 350. IP packets from thecontroller/processor 375 may be provided to the EPC 160. Thecontroller/processor 375 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

At least one of the TX processor 368, the RX processor 356, and thecontroller/processor 359 may be configured to perform aspects inconnection with 198 or 199 of FIG. 1.

At least one of the TX processor 316, the RX processor 370, and thecontroller/processor 375 may be configured to perform aspects inconnection with 198 or 199 of FIG. 1.

In wireless communication systems, a UE may lose coverage due to aslosing the connection or Uu link with a base station. In some instances,one or more relays with a Uu connection with the base station may bewithin range of the UE that lost coverage. The relay and the UE may bein an RRC connected state, such that the UE may select one of the relaysand establishes a PC5 connection with the selected source relay. The UEmay then be able to communicate with the base station through the sourcerelay. For example, with reference to the example 400 of FIG. 4, aremote UE 402 may lose its Uu link 408 with the base station 404. Relay1 406 and Relay 2 406 may be within range of the UE 402, such that theUE 402 may establish a PC5 connection 410 with one of Relay 1 406 orRelay 2 406.

In some instances, the PC5 connection with the source relay (e.g., Relay1 406) may become weak, and the remote UE 402 may switch to anotherrelay (e.g., Relay 2 406). In such instances, the Relay 1 406 mayencounter radio link failure on its Uu link 408 with the base station404, such that the PC5 link 410 between the Relay 1 406 and the UE 402is no longer good. The PC5 link 410 between the Relay 1 406 and the UE402 may degrade or weaken due to the Relay 1 406 being beyond the rangeof the UE 402.

FIG. 5 illustrates an example 500 of radio link failure of a relaydevice. The example 500 includes a UE 1 502, a UE 2 502, a source relay506, and a base station 504. As shown in the example 500 of FIG. 5, theUE 1 502 and UE 2 502 may be in a connected state (e.g., 508) with thesource relay 506. In some instances, the source relay 506 may experiencefailure on its Uu link with the base station (e.g., 504) while connectedwith the UE 1 502 and UE 2 502. The source relay 506 may experiencefailure on its Uu link for a variety of reasons, such as but not limitedto, Uu radio link failure, Uu handover failure, or Uu reconfigurationfailure. The source relay 506, at 510, may detect the radio link failureand may trigger reestablishment upon the detection the radio linkfailure. The source relay 506 may enter an idle mode (e.g., 512) afterdetecting the radio link failure. The base station 504, at 514, mayrelease the UE context of the source relay 506 and associated connectedUEs (e.g., UE 1 502 and UE 2 502) upon the expiration of a relayinactivity timer.

The source relay 506 may handle the PC5 links with the UE1 502 and UE 2502 by releasing or suspending the PC5 link. For example, the sourcerelay 506 may send a sidelink command (e.g., 516) to release or suspendthe PC5 link with any active UFs (e.g., UE 1 502 and UE 2 502), suchthat the active UEs (e.g., UE 1 502 and UE 2 502) enter an idle state(e.g., 518). In addition, the source relay 506 may stop advertising thesupport of relaying in discovery messages. After a successful Uu linksetup, the source relay 506 may resume the suspended PC5 links with theUEs (e.g., UE 1 502 and UE 2 502), and may follow the relayadvertisement criteria to resume advertising support for relay service.

When a source relay experiences radio link failure, the connected UE mayinitiate a relay switching mechanism. For example, the UE may determinea radio link failure with the source relay after the source relayreleases the PC5 link with the UE. The UE may search for a new sourcerelay. In some instances, the UE may receive RRC reconfiguration toswitch to a new relay. The RRC reconfiguration may be sent to the UEfrom the source relay. The source relay, in response, may suspend theactive PC5 link with the UE and may resume the active PC5 link after therelay successfully recovers its Uu link with the base station. The PC5link between the source relay and the UE may fail or may not be areliable connection, such that the UE may initiate the relay switchingmechanism. However, the relay switching mechanism may incur a longswitching latency.

Aspects presented herein provide a configuration for an improved relaymeasurement mechanism. The improved relay measurement mechanism mayconfigure a UE with a relay measurement configuration for measuring oneor more candidate relays in preparation of switching to a target relay.At least one advantage of the disclosure is that the relay measurementconfiguration may allow the UE to account for candidate relays that arewithin a bandwidth for communicating with a source relay as well as forcandidate relays that are not within a bandwidth for communicating withthe source relay.

In some aspects, a source relay may indicate a configuration ofcandidate relays to a UE. The configuration of candidate relays mayinclude information related to the candidate relays, such as but notlimited to a relay identifier or resource pool for discovery. In someaspects, a base station having a Uu connection with the source relay maydetermine which relays may serve as candidate relays. The base stationmay then send the information of the candidate relays to the sourcerelay, such that the source relay sends the information of the candidaterelays to the UE. In some aspects, the source relay may be configured toevaluate the relays and determine a list of candidate relays. The sourcerelay may determine the list of candidate relays on its own and withoutinput from the base station.

The configuration of candidate relays may further include a relaymeasurement configuration. The relay measurement configuration maycomprise an indication of a measurement gap configuration. Theindication of the measurement gap configuration may indicate whethercandidate relays are within a bandwidth configured for communicationbetween the UE and the source relay. For example, with reference to theexample 600 of FIG. 6A, the reference signals R1, R2, Rn (e.g., 604) forthe corresponding candidate relays are within the bandwidth 602, whichis the bandwidth 602 configured for communication between the UE and thesource relay. The reference signals (e.g., R1 604, R2 604, . . . Rn 604)from candidate relays for RSRP measurement are within the bandwidth 602configured for communication between the UE and the source relay. In theexample 600 of FIG. 6A, a measurement gap is not needed if sub-carrierspacings of reference signals are identical. Otherwise, a measurementgap should be provided.

In some instances, the reference signals from some of the candidaterelays may not be within an operating bandwidth configured forcommunication between the UE and the source relay. For example, as shownin the example 610 of FIG. 6B, the reference signal R2 606 is not withinthe bandwidth 602 configured for communication between the UE and thesource relay, while reference signals R1 604 and Rn 604 are within thebandwidth 602. In such instances, a measurement gap should be provided.The measurement gap allows the UE to tune away from the bandwidth tomeasure the reference signal (e.g., R2 606) of the candidate relay thatis outside of the bandwidth 602. In some instances, reference signalsfrom the candidate relays that are outside of the bandwidth (e.g., 602)may comprise a different numerology than the source relay.

In some aspects, a measurement gap may not be defined for intra-cellrelay measurements. Measurement resources allocated for the relays maybe within the operating bandwidth (e.g., 602) that the UE uses forcommunicating with the source relay. Measurement of reference signals orchannels from the candidate relays may have the same numerology. If themeasurement resource is outside of the operating bandwidth (e.g., 602)that the UE uses for communicating with the source relay, then the UEmay not measure such measurement resource.

In some aspects, a measurement gap may be configured for intra-cellrelay measurements. Measurement resources allocated for a candidaterelay may be configured to be outside of the operating bandwidth (e.g.,602) that the UE uses for communicating with the source relay. In someinstances, the measurement of reference signals or channels from thecandidate relays may have a different numerology. If the measurement ofreference signal or channel from the candidate relays have a differentnumerology, the numerology used to define the measurement gap may bebased on the numerology of the physical channel or bandwidth that isassociated with the source relay, or the numerology of the referencechannel associated with the candidate relay. In some aspects, themeasurement gap may be common for reference signals having the samenumerology. The measurement gap configuration may be configured as partof a relay indication or part of a PC5 establishment procedure.

The UE may be configured to measure reference signals from the sourcerelay and the list of candidate relays. The UE may be triggered toperform such measurement under certain conditions, such as for example,if the signal measurement of the source relay is below a threshold. Thethreshold may be preconfigured or may be configured by the source relayor the base station. The UE may measure DMRS of discovery channel formthe source relay and the candidate relays. The UE may be configured torank the candidate relays based on the signal measurements. The UE mayestablish a PC5 connection with the list of candidate relays when someconditions are met. For example, the RSRP of the source relaymaintaining a range of value or meeting a threshold. In some aspects,information related to the list of candidate relays may be indicated tothe UE in the configuration of candidate relays. In some aspects, the UEmeasures each of the candidate relays, such that the UE may select asubset of candidate relays from the list of candidate relays toestablish the PC5 connection. The subset of candidate relays may be lessthan or equal to the list of candidate relays.

The UE may send a measurement report to the source relay. Themeasurement report may include measurements of the list of candidaterelays and measurements of the source relay. In some aspects, the sourcerelay may transmit the measurement report, received from the UE, to thebase station. In such aspects, the base station may determine the targetrelay based on the measurement report. The base station may thentransmit, to the source relay, an indication of the target relay fromthe list of candidate relays. The base station may also send, to thesource relay, a relay switch command indicating the UE to switch to thetarget relay. The source relay, in turn, provides the relay switchcommand to the UE.

In some aspects, the source relay may be configured to determine thetarget relay. The source relay may be configured to determine the targetrelay based on the measurement report received from the UE. The sourcerelay may determine the target relay without input from the basestation. The source relay transmits the relay switch command to the UEto indicate the switch to the target relay.

The UE switches to the target relay, in response to receiving the relayswitch command from the source relay. The source relay may transmit therelay switch command to the UE in sidelink control information (SCI) orPC5 medium access control (MAC) control element (CE) (MAC-CE). Thetransmission of the relay switch command using SCI or PC5 MAC-CEcomprise Layer-1 or Layer-2 signaling which leads to a significantreduction of time.

In some aspects, the measurement report generated by the UE may comprisea Layer-1 measurement, such as but not limited to a Layer-1 RSRP of adiscovery signal of the source relay. In some aspects, the UE may betriggered by an event to perform the measurements of the source relayand list of candidate relays and generate the measurement report. Forexample, the event triggering the UE to perform the measurement may bebased on the certain conditions of the source relay, such as forexample, the measurement of RSRP against a threshold. In some aspects,the measurement of the source relay and candidate relays may beconfigured to be periodic. In some aspects, the measurement of thesource relay and candidate relays may be configured to be aperiodic,such that the UE may be triggered by the network to perform themeasurements. The source relay may indicate, to the UE, whichmeasurement report type should be utilized by the UE. In some aspects,the measurement report may be carried over physical sidelink controlchannel (PSCCH) or physical sidelink shared channel (PSSCH).

FIG. 7 is a call flow diagram 700 of signaling between a UE 702, a basestation 704, and a source relay 706. The base station 704 or the sourcerelay 706 may be configured to provide a cell. The UE 702 may beconfigured to communicate with the base station 704 or the source relay706. For example, in the context of FIG. 1, the base station 704 or thesource relay 706 may correspond to base station 102/180 and,accordingly, the cell may include a geographic coverage area 110 inwhich communication coverage is provided and/or small cell 102′ having acoverage area 110′. Further, a UE 702 or source relay 706 may correspondto at least UE 104. In another example, in the context of FIG. 3, thebase station 704 or source relay 706 may correspond to base station 310,and the UE 702 or source relay 706 may correspond to UE 350.

As illustrated at 708, the base station 704 may configure a candidaterelay configuration including information of candidate relays (notshown) and a relay measurement configuration. The relay measurementconfiguration may comprise an indication of a measurement gapconfiguration. The indication of the measurement gap configuration mayindicate whether candidate relays may be within a bandwidth configuredfor communication between the UE 702 and the source relay 706. In someaspects, the measurement gap configuration may not be provided forreference signals from candidate relays having a same SCS as the sourcerelay 706. The reference signals from the candidate relays may be withinan operating bandwidth configured for communication between the UE 702and the source relay 706. A measurement gap may not be utilized forinstances where the SCSs of the reference signals from the candidaterelays are the same as the source relay. A measurement gap may beprovided and utilized for instances where the SCSs of the referencesignals from the candidate relays are different than that of the sourcerelay. The measurement gap may be indicated in the measurementconfiguration. Measurement resources allocated for the candidate relaysmay be within the bandwidth configured for communication between the UE702 and the source relay 706. The reference signals from the candidaterelays may have a same numerology as the source relay. In some aspects,the measurement gap configuration may indicate that a measurement gapmay be utilized for reference signals from candidate relays that may notbe within the bandwidth configured for communication between the UE 702and the source relay 706. In such aspects, the reference signals fromthe candidate relays may not be within an operating bandwidth configuredfor communication between the UE 702 and the source relay 706.Measurement resources allocated for the candidate relays may beconfigured to be outside of the bandwidth configured for communicationbetween the UE 702 and the source relay 706. In some aspects, referencesignals from the candidate relays may comprise a different numerologythan the source relay. A numerology used for the measurement gap may bebased on a numerology of a physical channel or bandwidth associated withthe source relay 706. In some aspects, a numerology used for themeasurement gap may be based on a numerology of a reference channelassociated with at least one of the candidate relays. The measurementgap may be common for reference signals from candidate relays with thesame numerology.

As illustrated at 710, the base station 704 may transmit the candidaterelay configuration. The base station 704 may transmit the candidaterelay configuration to the source relay 706. The source relay 706 mayreceive the candidate relay configuration from the base station 704. Insome aspects, the base station 704 may determine a list of candidatesrelays for the candidate relay configuration.

As illustrated at 712, the source relay 706 may determine the list ofcandidate relays. In some aspects, the source relay 706 may determinethe list of candidate relays for the candidate relay configuration.

As illustrated at 714, the source relay 706 may transmit the candidaterelay configuration. The source relay may transmit the candidate relayconfiguration to the UE 702. The UE 702 may receive the candidate relayconfiguration from the source relay 706. The candidate relayconfiguration may include information of candidate relays and the relaymeasurement configuration. In some aspects, a subset of candidate relaysmay be provided to the UE 702 in the candidate relay configuration. Insome aspects, the source relay 706 may comprise a UE. In some aspects,the source relay 706 may comprise a base station.

As illustrated at 716, the UE 702 may measure a reference signal of thesource relay 706 and each of the candidate relays based on the candidaterelay configuration. In some aspects, measuring the reference signal maycomprise measuring a demodulated reference signal (DMRS) of a discoverychannel from the source relay 706 and each of the candidate relays.

As illustrated at 718, the UE 702 may tune away from the bandwidthconfigured for communication between the UE 702 and the source relay706. The UE 702 tune away from the bandwidth configured forcommunication between the UE 702 and source relay 706 to measure areference signal from at least one candidate relay that is not withinthe bandwidth configured for communication between the UE 702 and thesource relay 706.

As illustrated at 720, the UE 702 may transmit a measurement report. TheUE 702 may transmit the measurement report to the source relay 706. Thesource relay 706 may receive the measurement report from the UE 702. Themeasurement report may comprise measurements of the reference signal ofthe subset of candidate relays. In some aspects, the measurement reportmay comprise a measurement of a layer 1 reference signal receive power(RSRP) of the source relay 706 and the subset of candidate relays. Themeasurement report may be carried over physical sidelink control channel(PSCCH) or physical sidelink shared channel (PSSCH).

As illustrated at 722, the UE 702 may establish a connection with asubset of candidate relays. In some aspects, the connection with thesubset of candidate relays may comprise a PC5 connection. The UE 702 mayestablish the connection with the subset of candidate relays inpreparation of switching to a target relay from the subset of candidaterelays.

As illustrated at 724, the source relay 706 may transmit the measurementreport to the base station 704. The source relay 706 may transmit, tothe base station 704, the measurement report received from the UE 702.The base station 704 may receive the measurement report from the sourcerelay 706.

As illustrated at 726, the base station 704 may select a target relay.The base station 704 may select the target relay from the subset ofcandidate relays. The base station 704 may select the target relay fromthe subset of candidate relays based on the measurement report.

In some aspects, the source relay 706 may receive an indication of atarget relay. The source relay 706 may receive the indication of thetarget relay from the base station 704. The indication may indicate thetarget relay from the subset of candidate relays. In some aspects, thebase station 704 may determine the target relay from the subset ofcandidate relays based on the measurement report.

As illustrated at 728, the base station 704 may transmit the relayswitch command.

The base station 704 may transmit the relay switch command to the sourcerelay 706. The source relay 706 may receive the relay switch commandfrom the base station 704. The relay switch command may be for the UE702 to switch to the target relay. In some aspects, the relay switchcommand may be transmitted via Layer-1 or Layer-2 signaling. The Layer-1signaling may comprise control information or sidelink controlinformation. The Layer-2 signaling may comprise MAC-CE. In some aspects,the target relay information may be indicated in the relay switchcommand. As illustrated at 730, the source relay 706 may transmit therelay switch command. The source relay 706 may transmit the relay switchcommand to the UE 702. The UE 702 may receive the relay switch commandfrom the source relay 706. The relay switch command may indicate the UE702 to switch to a target relay from the subset of candidate relays. Insome aspects, the target relay information may be indicated in the relayswitch command. In some aspects, the source relay 706 may determine thetarget relay based on the measurement report. In some aspects, the relayswitch command may be received via Layer-1 or Layer-2 signaling. TheLayer-1 signaling may comprise control information or sidelink controlinformation. The Layer-2 signaling may comprise medium access control(MAC) control element (CE) (MAC-CE). In some aspects, the target relayinformation may be indicated in the relay switch command. In someaspects, the base station 704 may determine the target relay from thesubset of candidate relays based on the measurement report. In someaspects, the source relay 706 may determine the target relay based onthe measurement report.

As illustrated at 732, the UE 702 may switch to the target relay. The UE702 may switch to the target relay as indicted in the relay switchcommand.

FIG. 8 is a flowchart 800 of a method of wireless communication. Themethod may be performed by a UE or a component of a UE (e.g., the UE104; the apparatus 1002; the cellular baseband processor 1004, which mayinclude the memory 360 and which may be the entire UE 350 or a componentof the UE 350, such as the TX processor 368, the RX processor 356,and/or the controller/processor 359). One or more of the illustratedoperations may be omitted, transposed, or contemporaneous. The methodmay configure the UE with a relay measurement configuration formeasuring one or more candidate relays in preparation of switching to atarget relay.

At 802, the UE may receive a candidate relay configuration. For example,802 may be performed by candidate relay component 1040 of apparatus1002. The UE may receive the candidate relay configuration from a sourcerelay. The candidate relay configuration may include information ofcandidate relays and a relay measurement configuration. In some aspects,the relay measurement configuration may comprise an indication of ameasurement gap configuration. The indication of the measurement gapconfiguration may indicate whether candidate relays are within abandwidth configured for communication between the UE and the sourcerelay. In some aspects, the measurement gap configuration may not beprovided for reference signals from candidate relays having a samesub-carrier spacing (SCS) as the source relay. In such aspects, thereference signals from the candidate relays may be within an operatingbandwidth configured for communication between the UE and the sourcerelay. A measurement gap may not be utilized for instances where theSCSs of the reference signals from the candidate relays are the same asthe source relay. A measurement gap may be provided and utilized forinstances where the SCSs of the reference signals from the candidaterelays are different than that of the source relay. The measurement gapmay be indicated in the measurement configuration. Measurement resourcesallocated for the candidate relays may be within the bandwidthconfigured for communication between the UE and the source relay. Thereference signals from the candidate relays may have a same numerologyas the source relay. In some aspects, the measurement gap configurationmay indicate that a measurement gap may be utilized for referencesignals from candidate relays that are not within the bandwidthconfigured for communication between the UE and the source relay. Insuch aspects, the reference signals from the candidate relays may not bewithin an operating bandwidth configured for communication between theUE and the source relay. Measurement resources allocated for thecandidate relays may be configured to be outside of the bandwidthconfigured for communication between the UE and the source relay. Insome aspects, the reference signals from the candidate relays maycomprise a different numerology than the source relay. A numerology usedfor the measurement gap may be based on a numerology of a physicalchannel or bandwidth associated with the source relay. In some aspects,a numerology used for the measurement gap may be based on a numerologyof a reference channel associated with the candidate relay. Themeasurement gap may be common for reference signals from candidaterelays with a same numerology.

At 804, the UE may measure a reference signal of the source relay andeach of the candidate relays based on the candidate relay configuration.For example, 804 may be performed by measure component 1042 of apparatus1002. In some aspects, measuring the reference signal may comprisemeasuring a demodulated reference signal (DMRS) of a discovery channelfrom the source relay and each of the candidate relays.

At 806, the UE may transmit a measurement report. For example, 806 maybe performed by report component 1046 of apparatus 1002. The UE maytransmit the measurement report to the source relay. The measurementreport may comprise measurements of the reference signal of the subsetof candidate relays. In some aspects, the measurement report maycomprise a measurement of a layer 1 reference signal receive power(RSRP) of the source relay and the subset of candidate relays. Themeasurement report may be carried over physical sidelink control channel(PSCCH) or physical sidelink shared channel (PSSCH).

At 808, the UE may establish a connection with a subset of candidaterelays. For example, 808 may be performed by connection component 1048of apparatus 1002. In some aspects, the connection with the subset ofcandidate relays may comprise a PC5 connection.

At 810, the UE may receive a relay switch command. For example, 810 maybe performed by switch component 1050 of apparatus 1002. The UE mayreceive the relay switch command from the source relay. The relay switchcommand may indicate to the UE to switch to a target relay from thesubset of candidate relays. In some aspects, the relay switch commandmay be received via Layer-1 or Layer-2 signaling. The Layer-1 signalingmay comprise control information or sidelink control information. TheLayer-2 signaling may comprise medium access control (MAC) controlelement (CE) (MAC-CE). In some aspects, the target relay information maybe indicated in the relay switch command. In some aspects, the basestation may determine the target relay from the subset of candidaterelays based on the measurement report. In some aspects, the sourcerelay may determine the target relay based on the measurement report.

FIG. 9 is a flowchart 900 of a method of wireless communication. Themethod may be performed by a UE or a component of a UE (e.g., the UE104; the apparatus 1002; the cellular baseband processor 1004, which mayinclude the memory 360 and which may be the entire UE 350 or a componentof the UE 350, such as the TX processor 368, the RX processor 356,and/or the controller/processor 359). One or more of the illustratedoperations may be omitted, transposed, or contemporaneous. The methodmay configure the UE with a relay measurement configuration formeasuring one or more candidate relays in preparation of switching to atarget relay.

At 902, the UE may receive a candidate relay configuration. For example,902 may be performed by candidate relay component 1040 of apparatus1002. The UE may receive the candidate relay configuration from a sourcerelay. The candidate relay configuration may include information ofcandidate relays and a relay measurement configuration. In some aspects,the relay measurement configuration may comprise an indication of ameasurement gap configuration. The indication of the measurement gapconfiguration may indicate whether candidate relays are within abandwidth configured for communication between the UE and the sourcerelay. In some aspects, the measurement gap configuration may not beprovided for reference signals from candidate relays having a samesub-carrier spacing (SCS) as the source relay. In such aspects, thereference signals from the candidate relays may be within an operatingbandwidth configured for communication between the UE and the sourcerelay. A measurement gap may not be utilized for instances where theSCSs of the reference signals from the candidate relays are the same asthe source relay. A measurement gap may be provided and utilized forinstances where the SCSs of the reference signals from the candidaterelays are different than that of the source relay. The measurement gapmay be indicated in the measurement configuration. Measurement resourcesallocated for the candidate relays may be within the bandwidthconfigured for communication between the UE and the source relay. Thereference signals from the candidate relays may have a same numerologyas the source relay. In some aspects, the measurement gap configurationmay indicate that a measurement gap may be utilized for referencesignals from candidate relays that are not within the bandwidthconfigured for communication between the UE and the source relay. Insuch aspects, the reference signals from the candidate relays may not bewithin an operating bandwidth configured for communication between theUE and the source relay. Measurement resources allocated for thecandidate relays may be configured to be outside of the bandwidthconfigured for communication between the UE and the source relay. Insome aspects, the reference signals from the candidate relays maycomprise a different numerology than the source relay. A numerology usedfor the measurement gap may be based on a numerology of a physicalchannel or bandwidth associated with the source relay. In some aspects,a numerology used for the measurement gap may be based on a numerologyof a reference channel associated with the candidate relay. Themeasurement gap may be common for reference signals from candidaterelays with a same numerology.

At 904, the UE may measure a reference signal of the source relay andeach of the candidate relays based on the candidate relay configuration.For example, 904 may be performed by measure component 1042 of apparatus1002. In some aspects, measuring the reference signal may comprisemeasuring a DMRS of a discovery channel from the source relay and eachof the candidate relays.

At 906, the UE may tune away from the bandwidth configured forcommunication between the UE and source relay. For example, 906 may beperformed by tune component 1044 of apparatus 1002. The UE tune awayfrom the bandwidth configured for communication between the UE andsource relay to measure a reference signal from at least one candidaterelay that is not within the bandwidth configured for communicationbetween the UE and the source relay.

At 908, the UE may transmit a measurement report. For example, 908 maybe performed by report component 1046 of apparatus 1002. The UE maytransmit the measurement report to the source relay. The measurementreport may comprise measurements of the reference signal of the subsetof candidate relays. In some aspects, the measurement report maycomprise a measurement of a layer 1 RSRP of the source relay and thesubset of candidate relays. The measurement report may be carried overPSCCH or PSSCH.

At 910, the UE may establish a connection with a subset of candidaterelays. For example, 910 may be performed by connection component 1048of apparatus 1002. In some aspects, the connection with the subset ofcandidate relays may comprise a PC5 connection.

At 912, the UE may receive a relay switch command. For example, 912 maybe performed by switch component 1050 of apparatus 1002. The UE mayreceive the relay switch command from the source relay. The relay switchcommand may indicate to the UE to switch to a target relay from thesubset of candidate relays. In some aspects, the relay switch commandmay be received via Layer-1 or Layer-2 signaling. The Layer-1 signalingmay comprise control information or sidelink control information. TheLayer-2 signaling may comprise MAC-CE. In some aspects, the target relayinformation may be indicated in the relay switch command. In someaspects, the base station may determine the target relay from the subsetof candidate relays based on the measurement report. In some aspects,the source relay may determine the target relay based on the measurementreport.

At 914, the UE may switch to the target relay. For example, 914 may beperformed by target relay component 1052 of apparatus 1002. The UE mayswitch to the target relay as indicted in the relay switch command.

FIG. 10 is a diagram 1000 illustrating an example of a hardwareimplementation for an apparatus 1002. The apparatus 1002 may be a UE, acomponent of a UE, or may implement UE functionality. In some aspects,the apparatus 1002 may include a cellular baseband processor 1004 (alsoreferred to as a modem) coupled to a cellular RF transceiver 1022. Insome aspects, the apparatus 1002 may further include one or moresubscriber identity modules (SIM) cards 1020, an application processor1006 coupled to a secure digital (SD) card 1008 and a screen 1010, aBluetooth module 1012, a wireless local area network (WLAN) module 1014,a Global Positioning System (GPS) module 1016, or a power supply 1018.The cellular baseband processor 1004 communicates through the cellularRF transceiver 1022 with the UE 104 and/or BS 102/180. The cellularbaseband processor 1004 may include a computer-readable medium/memory.The computer-readable medium/memory may be non-transitory. The cellularbaseband processor 1004 is responsible for general processing, includingthe execution of software stored on the computer-readable medium/memory.The software, when executed by the cellular baseband processor 1004,causes the cellular baseband processor 1004 to perform the variousfunctions described supra. The computer-readable medium/memory may alsobe used for storing data that is manipulated by the cellular basebandprocessor 1004 when executing software. The cellular baseband processor1004 further includes a reception component 1030, a communicationmanager 1032, and a transmission component 1034. The communicationmanager 1032 includes the one or more illustrated components. Thecomponents within the communication manager 1032 may be stored in thecomputer-readable medium/memory and/or configured as hardware within thecellular baseband processor 1004. The cellular baseband processor 1004may be a component of the UE 350 and may include the memory 360 and/orat least one of the TX processor 368, the RX processor 356, and thecontroller/processor 359. In one configuration, the apparatus 1002 maybe a modem chip and include just the baseband processor 1004, and inanother configuration, the apparatus 1002 may be the entire UE (e.g.,see 350 of FIG. 3) and include the additional modules of the apparatus1002. The communication manager 1032 includes a candidate relaycomponent 1040 that is configured to receive a candidate relayconfiguration, e.g., as described in connection with 802 of FIG. 8 or902 of FIG. 9. The communication manager 1032 further includes a measurecomponent 1042 that is configured to measure a reference signal of thesource relay and each of the candidate relays based on the candidaterelay configuration, e.g., as described in connection with 804 of FIG. 8or 904 of FIG. 9. The communication manager 1032 further includes a tunecomponent 1044 that is configured to tune away from the bandwidthconfigured for communication between the UE and source relay, e.g., asdescribed in connection with 906 of FIG. 9. The communication manager1032 further includes a report component 1046 that is configured totransmit a measurement report, e.g., as described in connection with 806of FIG. 8 or 908 of FIG. 9. The communication manager 1032 furtherincludes a connection component 1048 that is configured to establish aconnection with a subset of candidate relays, e.g., as described inconnection with 808 of FIG. 8 or 910 of FIG. 9. The communicationmanager 1032 further includes a switch component 1050 that is configuredto receive a relay switch command, e.g., as described in connection with810 of FIG. 8 or 912 of FIG. 9. The communication manager 1032 furtherincludes a target relay component 1052 that is configured to switch tothe target relay, e.g., as described in connection with 914 of FIG. 9.

The apparatus may include additional components that perform each of theblocks of the algorithm in the flowcharts of FIGS. 8 and 9. As such,each block in the flowcharts of FIGS. 8 and 9 may be performed by acomponent and the apparatus may include one or more of those components.The components may be one or more hardware components specificallyconfigured to carry out the stated processes/algorithm, implemented by aprocessor configured to perform the stated processes/algorithm, storedwithin a computer-readable medium for implementation by a processor, orsome combination thereof.

As shown, the apparatus 1002 may include a variety of componentsconfigured for various functions. In one configuration, the apparatus1002, and in particular the cellular baseband processor 1004, includesmeans for receiving, from a source relay, a candidate relayconfiguration. The candidate relay configuration including informationof candidate relays and a relay measurement configuration. The apparatusincludes means for measuring a reference signal of the source relay andeach of the candidate relays based on the candidate relay configuration.The apparatus includes means for transmitting, to the source relay, ameasurement report of the reference signal of the subset of candidaterelays. The apparatus includes means for establishing a connection witha subset of candidate relays. The apparatus includes means forreceiving, from the source relay, a relay switch command to switch to atarget relay from the subset of candidate relays. The apparatus furtherincludes means for tuning away from the bandwidth configured forcommunication between the UE and source relay to measure a referencesignal from at least one candidate relay that is not within thebandwidth configured for communication between the UE and the sourcerelay. The apparatus further includes means for switching to the targetrelay as indicated in the relay switch command. The means may be one ormore of the components of the apparatus 1002 configured to perform thefunctions recited by the means. As described supra, the apparatus 1002may include the TX Processor 368, the RX Processor 356, and thecontroller/processor 359. As such, in one configuration, the means maybe the TX Processor 368, the RX Processor 356, and thecontroller/processor 359 configured to perform the functions recited bythe means. FIG. 11 is a flowchart 1100 of a method of wirelesscommunication. The method may be performed by a UE or a component of aUE (e.g., the UE 104, 402, 502, 702; source relay 406, 506, 706; theapparatus 1302; the baseband unit 1304, which may include the memory 376and which may be the entire base station 310 or a component of the basestation 310, such as the TX processor 316, the RX processor 370, and/orthe controller/processor 375). The method may also be performed by abase station or a component of a base station (e.g., the base station102/180, 404, 504, 704; source relay 406, 506, 706; the apparatus 1302;the baseband unit 1304, which may include the memory 376 and which maybe the entire base station 310 or a component of the base station 310,such as the TX processor 316, the RX processor 370, and/or thecontroller/processor 375). One or more of the illustrated operations maybe omitted, transposed, or contemporaneous. The method may allow asource relay to configure a UE with a relay measurement configurationfor measuring one or more candidate relays in preparation of switchingto a target relay.

At 1102, the source relay may transmit the candidate relayconfiguration. For example, 1102 may be performed by configurationcomponent 1344 of apparatus 1302. The source relay may transmit thecandidate relay configuration to a UE. The candidate relay configurationmay include information of candidate relays and a relay measurementconfiguration. The relay measurement configuration may comprise anindication of a measurement gap configuration. In some aspects, theindication of the measurement gap configuration may indicate whethercandidate relays may be within a bandwidth configured for communicationbetween the UE and the source relay. In such aspects, the measurementgap configuration may indicate that a measurement gap may not beutilized for reference signals from candidate relays having a same SCSas the source relay. The reference signals from the candidate relays maybe within an operating bandwidth configured for communication betweenthe UE and the source relay. Measurement resources allocated for thecandidate relays may be within the bandwidth configured forcommunication between the UE and the source relay. In some aspects, thereference signals from the candidate relays may have a same numerologyas the source relay. In some aspects, the measurement gap configurationmay indicate that a measurement gap may be utilized for referencesignals from candidate relays that may not be within the bandwidthconfigured for communication between the UE and the source relay. Thereference signals from the candidate relays may not be within anoperating bandwidth configured for communication between the UE and thesource relay. Measurement resources allocated for the candidate relaysmay be configured to be outside of the bandwidth configured forcommunication between the UE and the source relay. Reference signalsfrom the candidate relays may comprise a different numerology than thesource relay. In some aspects, a numerology used for the measurement gapmay be based on a numerology of a physical channel or bandwidthassociated with the source relay. In some aspects, a numerology used forthe measurement gap may be based on a numerology of a reference channelassociated with the candidate relay. The measurement gap may be commonfor reference signals from candidate relays with a same numerology. Insome aspects, a subset of candidate relays may be provided to the UE inthe candidate relay configuration. In some aspects, the source relay maycomprise a UE. In some aspects, the source relay may comprise a basestation.

At 1104, the source relay may receive a measurement report. For example,1104 may be performed by report component 1346 of apparatus 1302. Thesource relay may receive the measurement report from the UE. Themeasurement report may comprise measurements of a subset of candidaterelays. In some aspects, the measurement report may comprise ameasurement of a Layer-1 RSRP of the source relay and the subset ofcandidate relays. In some aspects, the measurement report is carriedover PSCCH or PSSCH.

At 1106, the source relay may transmit the relay switch command. Forexample, 1106 may be performed by switch component 1350 of apparatus1302. The source relay may transmit the relay switch command to the UE.The relay switch command may indicate the UE to switch to a target relayfrom the subset of candidate relays. In some aspects, the target relayinformation may be indicated in the relay switch command. In someaspects, the source relay may determine the target relay based on themeasurement report.

FIG. 12 is a flowchart 1200 of a method of wireless communication. Themethod may be performed by a UE or a component of a UE (e.g., the UE104, 402, 502, 702; source relay 406, 506, 706; the apparatus 1302; thebaseband unit 1304, which may include the memory 376 and which may bethe entire base station 310 or a component of the base station 310, suchas the TX processor 316, the RX processor 370, and/or thecontroller/processor 375). The method may also be performed by a basestation or a component of a base station (e.g., the base station102/180, 404, 504, 704; source relay 406, 506, 706; the apparatus 1302;the baseband unit 1304, which may include the memory 376 and which maybe the entire base station 310 or a component of the base station 310,such as the TX processor 316, the RX processor 370, and/or thecontroller/processor 375). One or more of the illustrated operations maybe omitted, transposed, or contemporaneous. The method may allow asource relay to configure a UE with a relay measurement configurationfor measuring one or more candidate relays in preparation of switchingto a target relay.

At 1202, the source relay may receive a candidate relay configuration.For example, 1202 may be performed by candidate relay component 1340 ofapparatus 1302. The source relay may receive the candidate relayconfiguration from a base station. In some aspects, the base station maydetermine a list of candidates relays for the candidate relayconfiguration.

At 1204, the source relay may determine a list of candidate relays. Forexample, 1204 may be performed by determination component 1342 ofapparatus 1302. The source relay may determine the list of candidaterelays for the candidate relay configuration. At 1206, the source relaymay transmit the candidate relay configuration. For example, 1206 may beperformed by configuration component 1344 of apparatus 1302. The sourcerelay may transmit the candidate relay configuration to a UE. Thecandidate relay configuration may include information of candidaterelays and a relay measurement configuration. The relay measurementconfiguration may comprise an indication of a measurement gapconfiguration. In some aspects, the indication of the measurement gapconfiguration may indicate whether candidate relays may be within abandwidth configured for communication between the UE and the sourcerelay. In such aspects, the measurement gap configuration may indicatethat a measurement gap may not be utilized for reference signals fromcandidate relays having a same SCS as the source relay. The referencesignals from the candidate relays may be within an operating bandwidthconfigured for communication between the UE and the source relay.Measurement resources allocated for the candidate relays may be withinthe bandwidth configured for communication between the UE and the sourcerelay. In some aspects, the reference signals from the candidate relaysmay have a same numerology as the source relay. In some aspects, themeasurement gap configuration may indicate that a measurement gap may beutilized for reference signals from candidate relays that may not bewithin the bandwidth configured for communication between the UE and thesource relay. The reference signals from the candidate relays may not bewithin an operating bandwidth configured for communication between theUE and the source relay. Measurement resources allocated for thecandidate relays may be configured to be outside of the bandwidthconfigured for communication between the UE and the source relay.Reference signals from the candidate relays may comprise a differentnumerology than the source relay. In some aspects, a numerology used forthe measurement gap may be based on a numerology of a physical channelor bandwidth associated with the source relay. In some aspects, anumerology used for the measurement gap may be based on a numerology ofa reference channel associated with the candidate relay. The measurementgap may be common for reference signals from candidate relays with asame numerology. In some aspects, a subset of candidate relays may beprovided to the UE in the candidate relay configuration. In someaspects, the source relay may comprise a UE. In some aspects, the sourcerelay may comprise a base station.

At 1208, the source relay may receive a measurement report. For example,1208 may be performed by report component 1346 of apparatus 1302. Thesource relay may receive the measurement report from the UE. Themeasurement report may comprise measurements of a subset of candidaterelays. In some aspects, the measurement report may comprise ameasurement of a Layer-1 RSRP of the source relay and the subset ofcandidate relays. In some aspects, the measurement report is carriedover PSCCH or PSSCH.

At 1210, the source relay may transmit the measurement report to a basestation. For example, 1210 may be performed by report component 1346 ofapparatus 1302. The source relay may transmit, to the base station, themeasurement report received from the UE.

At 1212, the source relay may receive an indication of a target relay.For example, 1212 may be performed by indication component 1348 ofapparatus 1302. The source relay may receive the indication of thetarget relay from the base station. The indication may indicate thetarget relay from the subset of candidate relays. In some aspects, thebase station may determine the target relay from the subset of candidaterelays based on the measurement report.

At 1214, the source relay may receive the relay switch command. Forexample, 1214 may be performed by switch component 1350 of apparatus1302. The source relay may receive the relay switch command from thebase station. In some aspects, the relay switch command may betransmitted to the UE via Layer-1 or Layer-2 signaling. The Layer-1signaling may comprise control information or sidelink controlinformation. The Layer-2 signaling may comprise MAC-CE.

At 1216, the source relay may transmit the relay switch command. Forexample, 1216 may be performed by switch component 1350 of apparatus1302. The source relay may transmit the relay switch command to the UE.The relay switch command may indicate the UE to switch to a target relayfrom the subset of candidate relays. In some aspects, the target relayinformation may be indicated in the relay switch command. In someaspects, the source relay may determine the target relay based on themeasurement report.

At 1202, the source relay may receive a candidate relay configuration.For example, 1202 may be performed by candidate relay component 1340 ofapparatus 1302. The source relay may receive the candidate relayconfiguration from a base station. In some aspects, the base station maydetermine a list of candidates relays for the candidate relayconfiguration.

At 1204, the source relay may determine a list of candidate relays. Forexample, 1204 may be performed by determination component 1342 ofapparatus 1302. The source relay may determine the list of candidaterelays for the candidate relay configuration. At 1206, the source relaymay transmit the candidate relay configuration. For example, 1206 may beperformed by configuration component 1344 of apparatus 1302. The sourcerelay may transmit the candidate relay configuration to a UE. Thecandidate relay configuration may include information of candidaterelays and a relay measurement configuration. The relay measurementconfiguration may comprise an indication of a measurement gapconfiguration. In some aspects, the indication of the measurement gapconfiguration may indicate whether candidate relays may be within abandwidth configured for communication between the UE and the sourcerelay. In such aspects, the measurement gap configuration may indicatethat a measurement gap may not be utilized for reference signals fromcandidate relays having a same SCS as the source relay. The referencesignals from the candidate relays may be within an operating bandwidthconfigured for communication between the UE and the source relay.Measurement resources allocated for the candidate relays may be withinthe bandwidth configured for communication between the UE and the sourcerelay. In some aspects, the reference signals from the candidate relaysmay have a same numerology as the source relay. In some aspects, themeasurement gap configuration may indicate that a measurement gap may beutilized for reference signals from candidate relays that may not bewithin the bandwidth configured for communication between the UE and thesource relay. The reference signals from the candidate relays may not bewithin an operating bandwidth configured for communication between theUE and the source relay. Measurement resources allocated for thecandidate relays may be configured to be outside of the bandwidthconfigured for communication between the UE and the source relay.Reference signals from the candidate relays may comprise a differentnumerology than the source relay. In some aspects, a numerology used forthe measurement gap may be based on a numerology of a physical channelor bandwidth associated with the source relay. In some aspects, anumerology used for the measurement gap may be based on a numerology ofa reference channel associated with the candidate relay. The measurementgap may be common for reference signals from candidate relays with asame numerology. In some aspects, a subset of candidate relays may beprovided to the UE in the candidate relay configuration. In someaspects, the source relay may comprise a UE. In some aspects, the sourcerelay may comprise a base station.

At 1208, the source relay may receive a measurement report. For example,1208 may be performed by report component 1346 of apparatus 1302. Thesource relay may receive the measurement report from the UE. Themeasurement report may comprise measurements of a subset of candidaterelays. In some aspects, the measurement report may comprise ameasurement of a Layer-1 RSRP of the source relay and the subset ofcandidate relays. In some aspects, the measurement report is carriedover PSCCH or PSSCH.

At 1210, the source relay may transmit the measurement report to a basestation. For example, 1210 may be performed by report component 1346 ofapparatus 1302. The source relay may transmit, to the base station, themeasurement report received from the UE.

At 1212, the source relay may receive an indication of a target relay.For example, 1212 may be performed by indication component 1348 ofapparatus 1302. The source relay may receive the indication of thetarget relay from the base station. The indication may indicate thetarget relay from the subset of candidate relays. In some aspects, thebase station may determine the target relay from the subset of candidaterelays based on the measurement report.

At 1214, the source relay may receive the relay switch command. Forexample, 1214 may be performed by switch component 1350 of apparatus1302. The source relay may receive the relay switch command from thebase station. In some aspects, the relay switch command may betransmitted to the UE via Layer-1 or Layer-2 signaling. The Layer-1signaling may comprise control information or sidelink controlinformation. The Layer-2 signaling may comprise MAC-CE.

At 1216, the source relay may transmit the relay switch command. Forexample, 1216 may be performed by switch component 1350 of apparatus1302. The source relay may transmit the relay switch command to the UE.The relay switch command may indicate the UE to switch to a target relayfrom the subset of candidate relays. In some aspects, the target relayinformation may be indicated in the relay switch command. In someaspects, the source relay may determine the target relay based on themeasurement report.

The communication manager 1332 includes a candidate relay component 1340that is configured to receive a candidate relay configuration, e.g., asdescribed in connection with 1202 of FIG. 12. The communication manager1332 further includes a determination component 1342 that is configuredto determine a list of candidate relays, e.g., as described inconnection with 1204 of FIG. 12. The communication manager 1332 furtherincludes a configuration component 1344 that is configured to transmitthe candidate relay configuration, e.g., as described in connection with1102 of FIG. 11 or 1206 of FIG. 12. The communication manager 1332further includes a report component 1346 that is configured to receive ameasurement report, e.g., as described in connection with 1104 of FIG.11 or 1208 of FIG. 12. The report component 1346 may be configured totransmit the measurement report to a base station, e.g., as described inconnection with 1210 of FIG. 12. The communication manager 1332 furtherincludes an indication component 1348 that is configured to receive anindication of a target relay, e.g., as described in 1212 of FIG. 12. Thecommunication manager 1332 further includes a switch component 1350 thatis configured to receive the relay switch command, e.g., as described inconnection with 1214 of FIG. 12. The switch component 1350 may beconfigured to transmit the relay switch command, e.g., as described inconnection with 1106 of FIG. 11 or 1216 of FIG. 12.

The apparatus may include additional components that perform each of theblocks of the algorithm in the flowcharts of FIGS. 11 and 12. As such,each block in the flowcharts of FIGS. 11 and 12 may be performed by acomponent and the apparatus may include one or more of those components.The components may be one or more hardware components specificallyconfigured to carry out the stated processes/algorithm, implemented by aprocessor configured to perform the stated processes/algorithm, storedwithin a computer-readable medium for implementation by a processor, orsome combination thereof.

As shown, the apparatus 1302 may include a variety of componentsconfigured for various functions. In one configuration, the apparatus1302, and in particular the baseband unit 1304, includes means fortransmitting, to a UE, a candidate relay configuration. The candidaterelay configuration including information of candidate relays and arelay measurement configuration. The apparatus includes means forreceiving, from the UE, a measurement report of a subset of candidaterelays. The apparatus includes means for transmitting, to the UE, arelay switch command to switch to a target relay from the subset ofcandidate relays. The apparatus further includes means for receiving,from the base station, the candidate relay configuration. The apparatusfurther includes means for determining a list of candidate relays forthe candidate relay configuration. The apparatus further includes meansfor receiving, from a base station, the relay switch command. Theapparatus further includes means for transmitting, to a base station,the measurement report received from the UE. The apparatus furtherincludes means for receiving, from the base station, an indication of atarget relay from the subset of candidate relays. The means may be oneor more of the components of the apparatus 1302 configured to performthe functions recited by the means. As described supra, the apparatus1302 may include the TX Processor 316, the RX Processor 370, and thecontroller/processor 375. As such, in one configuration, the means maybe the TX Processor 316, the RX Processor 370, and thecontroller/processor 375 configured to perform the functions recited bythe means. FIG. 14 is a flowchart 1400 of a method of wirelesscommunication. The method may be performed by a base station or acomponent of a base station (e.g., the base station 102/180, 404, 504,704; the apparatus 1502; the baseband unit 1504, which may include thememory 376 and which may be the entire base station 310 or a componentof the base station 310, such as the TX processor 316, the RX processor370, and/or the controller/processor 375). One or more of theillustrated operations may be omitted, transposed, or contemporaneous.The method may allow a base station to configure a UE with a relaymeasurement configuration for measuring one or more candidate relays inpreparation of switching to a target relay.

At 1402, the base station may configure a candidate relay configurationincluding information of candidate relays and a relay measurementconfiguration. For example, 1402 may be performed by configurationcomponent 1540 of apparatus 1502. The relay measurement configurationmay comprise an indication of a measurement gap configuration. Theindication of the measurement gap configuration may indicate whethercandidate relays may be within a bandwidth configured for communicationbetween the UE and the source relay. In some aspects, the measurementgap configuration may indicate that a measurement gap may not beutilized for reference signals from candidate relays having a same SCSas the source relay. The reference signals from the candidate relays maybe within an operating bandwidth configured for communication betweenthe UE and the source relay. Measurement resources allocated for thecandidate relays may be within the bandwidth configured forcommunication between the UE and the source relay. The reference signalsfrom the candidate relays may have a same numerology as the sourcerelay. In some aspects, the measurement gap configuration may indicatethat a measurement gap may be utilized for reference signals fromcandidate relays that may not be within the bandwidth configured forcommunication between the UE and the source relay. In such aspects, thereference signals from the candidate relays may not be within anoperating bandwidth configured for communication between the UE and thesource relay. Measurement resources allocated for the candidate relaysmay be configured to be outside of the bandwidth configured forcommunication between the UE and the source relay. In some aspects,reference signals from the candidate relays may comprise a differentnumerology than the source relay. A numerology used for the measurementgap may be based on a numerology of a physical channel or bandwidthassociated with the source relay. In some aspects, a numerology used forthe measurement gap may be based on a numerology of a reference channelassociated with at least one of the candidate relays. The measurementgap may be common for reference signals from candidate relays with thesame numerology.

At 1404, the base station may transmit the candidate relayconfiguration. For example, 1404 may be performed by candidate relaycomponent 1542 of apparatus 1502. The base station may transmit thecandidate relay configuration to the source relay.

At 1406, the base station may receive a measurement report. For example,1406 may be performed by report component 1544 of apparatus 1502. Thebase station may receive the measurement report from the source relay.The measurement report may include measurements of reference signals ofa subset of candidate relays. The measurement report may comprise ameasurement of a Layer-1 RSRP of the source relay and the subset ofcandidate relays. In some aspects, the measurement report may be carriedover PSCCH or PSSCH.

At 1408, the base station may select a target relay. For example, 1408may be performed by target relay component 1546 of apparatus 1502. Thebase station may select the target relay from the subset of candidaterelays. The base station may select the target relay from the subset ofcandidate relays based on the measurement report. At 1410, the basestation may transmit the relay switch command. For example, 1410 may beperformed by switch component 1548 of apparatus 1502. The base stationmay transmit the relay switch command to the source relay. The relayswitch command may be for a UE to switch to the target relay. In someaspects, the relay switch command may be transmitted via Layer-1 orLayer-2 signaling. The Layer-1 signaling may comprise controlinformation or sidelink control information. The Layer-2 signaling maycomprise MAC-CE. In some aspects, the target relay information may beindicated in the relay switch command.

FIG. 15 is a diagram 1500 illustrating an example of a hardwareimplementation for an apparatus 1502. The apparatus 1502 may be a basestation, a component of a base station, or may implement base stationfunctionality. In some aspects, the apparatus 1502 may include abaseband unit 1504. The baseband unit 1504 may communicate through acellular RF transceiver 1522 with the UE 104. The baseband unit 1504 mayinclude a computer-readable medium/memory. The baseband unit 1504 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory. The software, whenexecuted by the baseband unit 1504, causes the baseband unit 1504 toperform the various functions described supra. The computer-readablemedium/memory may also be used for storing data that is manipulated bythe baseband unit 1504 when executing software. The baseband unit 1504further includes a reception component 1530, a communication manager1532, and a transmission component 1534. The communication manager 1532includes the one or more illustrated components. The components withinthe communication manager 1532 may be stored in the computer-readablemedium/memory and/or configured as hardware within the baseband unit1504. The baseband unit 1504 may be a component of the base station 310and may include the memory 376 and/or at least one of the TX processor316, the RX processor 370, and the controller/processor 375.

The communication manager 1532 includes a configuration component 1540that may configure a candidate relay configuration including informationof candidate relays and a relay measurement configuration, e.g., asdescribed in connection with 1402 of FIG. 14. The communication manager1532 further includes a candidate relay component 1542 that may transmitthe candidate relay configuration, e.g., as described in connection with1404 of FIG. 14. The communication manager 1532 further includes areport component 1544 that may receive a measurement report, e.g., asdescribed in connection with 1406 of FIG. 14. The communication manager1532 further includes a target relay component 1526 that may select atarget relay, e.g., as described in connection with 1408 of FIG. 14. Thecommunication manager 1532 further includes a switch component 1548 thatmay transmit the relay switch command, e.g., as described in connectionwith 1410 of FIG. 14.

The apparatus may include additional components that perform each of theblocks of the algorithm in the flowchart of FIG. 14. As such, each blockin the flowchart of FIG. 14 may be performed by a component and theapparatus may include one or more of those components. The componentsmay be one or more hardware components specifically configured to carryout the stated processes/algorithm, implemented by a processorconfigured to perform the stated processes/algorithm, stored within acomputer-readable medium for implementation by a processor, or somecombination thereof.

As shown, the apparatus 1502 may include a variety of componentsconfigured for various functions. In one configuration, the apparatus1502, and in particular the baseband unit 1504, includes means forconfiguring a candidate relay configuration including information ofcandidate relays and a relay measurement configuration. The apparatusincludes means for transmitting, to a source relay, the candidate relayconfiguration. The apparatus includes means for receiving, from thesource relay, a measurement report of reference signals of a subset ofcandidate relays. The apparatus includes means for selecting a targetrelay from the subset of candidate relays based on the measurementreport. The apparatus includes means for transmitting, to the sourcerelay, a relay switch command for a UE to switch to the target relay.The means may be one or more of the components of the apparatus 1502configured to perform the functions recited by the means. As describedsupra, the apparatus 1502 may include the TX Processor 316, the RXProcessor 370, and the controller/processor 375. As such, in oneconfiguration, the means may be the TX Processor 316, the RX Processor370, and the controller/processor 375 configured to perform thefunctions recited by the means.

It is understood that the specific order or hierarchy of blocks in theprocesses/flowcharts disclosed is an illustration of example approaches.Based upon design preferences, it is understood that the specific orderor hierarchy of blocks in the processes/flowcharts may be rearranged.Further, some blocks may be combined or omitted. The accompanying methodclaims present elements of the various blocks in a sample order, and arenot meant to be limited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Terms such as “if,” “when,” and“while” should be interpreted to mean “under the condition that” ratherthan imply an immediate temporal relationship or reaction. That is,these phrases, e.g., “when,” do not imply an immediate action inresponse to or during the occurrence of an action, but simply imply thatif a condition is met then an action will occur, but without requiring aspecific or immediate time constraint for the action to occur. The word“exemplary” is used herein to mean “serving as an example, instance, orillustration.” Any aspect described herein as “exemplary” is notnecessarily to be construed as preferred or advantageous over otheraspects. Unless specifically stated otherwise, the term “some” refers toone or more. Combinations such as “at least one of A, B, or C,” “one ormore of A, B, or C,” “at least one of A, B, and C,” “one or more of A,B, and C,” and “A, B, C, or any combination thereof” include anycombination of A, B, and/or C, and may include multiples of A, multiplesof B, or multiples of C. Specifically, combinations such as “at leastone of A, B, or C,” “one or more of A, B, or C,” “at least one of A, B,and C,” “one or more of A, B, and C,” and “A, B, C, or any combinationthereof” may be A only, B only, C only, A and B, A and C, B and C, or Aand B and C, where any such combinations may contain one or more memberor members of A, B, or C. All structural and functional equivalents tothe elements of the various aspects described throughout this disclosurethat are known or later come to be known to those of ordinary skill inthe art are expressly incorporated herein by reference and are intendedto be encompassed by the claims. Moreover, nothing disclosed herein isintended to be dedicated to the public regardless of whether suchdisclosure is explicitly recited in the claims. The words “module,”“mechanism,” “element,” “device,” and the like may not be a substitutefor the word “means.” As such, no claim element is to be construed as ameans plus function unless the element is expressly recited using thephrase “means for.”

The following aspects are illustrative only and may be combined withother aspects or teachings described herein, without limitation.

Aspect 1 is an apparatus for wireless communication at a UE including atleast one processor coupled to a memory and configured to receive, froma source relay, a candidate relay configuration, the candidate relayconfiguration including information of candidate relays and a relaymeasurement configuration; measure a reference signal of the sourcerelay and each of the candidate relays based on the candidate relayconfiguration; transmit, to the source relay, a measurement report ofthe reference signal of a subset of candidate relays; establishing aconnection with a subset of candidate relays; and receive, from thesource relay, a relay switch command to switch to a target relay fromthe subset of candidate relays.

Aspect 2 is the apparatus of aspect 1, further including a transceivercoupled to the at least one processor.

Aspect 3 is the apparatus of any of aspects 1 and 2, further includesthat the relay measurement configuration comprises an indication of ameasurement gap configuration.

Aspect 4 is the apparatus of any of aspects 1-3, further includes thatthe indication of the measurement gap configuration indicates whethercandidate relays are within a bandwidth configured for communicationbetween the UE and the source relay.

Aspect 5 is the apparatus of any of aspects 1-4, further includes thatthe measurement gap configuration is not provided for reference signalsfrom candidate relays having a same SCS as the source relay.

Aspect 6 is the apparatus of any of aspects 1-5, further includes thatthe reference signals from the candidate relays are within an operatingbandwidth configured for communication between the UE and the sourcerelay.

Aspect 7 is the apparatus of any of aspects 1-6, further includes thatmeasurement resources allocated for the candidate relays are within thebandwidth configured for communication between the UE and the sourcerelay.

Aspect 8 is the apparatus of any of aspects 1-7, further includes thatthe reference signals from the candidate relays have a same numerologyas the source relay.

Aspect 9 is the apparatus of any of aspects 1-8, further includes thatthe measurement gap configuration indicates that a measurement gap isutilized for reference signals from candidate relays that are not withinthe bandwidth configured for communication between the UE and the sourcerelay.

Aspect 10 is the apparatus of any of aspects 1-9, further includes thatthe reference signals from the candidate relays are not within anoperating bandwidth configured for communication between the UE and thesource relay.

Aspect 11 is the apparatus of any of aspects 1-10, further includes thatmeasurement resources allocated for the candidate relays are configuredto be outside of the bandwidth configured for communication between theUE and the source relay.

Aspect 12 is the apparatus of any of aspects 1-11, further includes thatthe at least one processor is further configured to tune away from thebandwidth configured for communication between the UE and source relayto measure a reference signal from at least one candidate relay that isnot within the bandwidth configured for communication between the UE andthe source relay.

Aspect 13 is the apparatus of any of aspects 1-12, further includes thatreference signals from the candidate relays comprise a differentnumerology than the source relay.

Aspect 14 is the apparatus of any of aspects 1-13, further includes thata numerology used for the measurement gap is based on a numerology of aphysical channel or bandwidth associated with the source relay.

Aspect 15 is the apparatus of any of aspects 1-14, further includes thata numerology used for the measurement gap is based on a numerology of areference channel associated with the candidate relay.

Aspect 16 is the apparatus of any of aspects 1-15, further includes thatthe measurement gap is common for reference signals from candidaterelays with a same numerology.

Aspect 17 is the apparatus of any of aspects 1-16, further includes thatthe measuring the reference signal comprises measuring a DMRS of adiscovery channel from the source relay and each of the candidaterelays.

Aspect 18 is the apparatus of any of aspects 1-17, further includes thatthe measurement report comprises a measurement of a layer 1 RSRP of thesource relay and the subset of candidate relays.

Aspect 19 is the apparatus of any of aspects 1-18, further includes thatthe measurement report is carried over PSCCH or PSSCH.

Aspect 20 is the apparatus of any of aspects 1-19, further includes thatthe connection with the subset of candidate relays comprises a PC5connection.

Aspect 21 is the apparatus of any of aspects 1-20, further includes thatthe relay switch command is received via Layer-1 or Layer-2 signaling.

Aspect 22 is the apparatus of any of aspects 1-21, further includes thatthe Layer-1 signaling comprises control information or sidelink controlinformation.

Aspect 23 is the apparatus of any of aspects 1-22, further includes thatthe Layer-2 signaling comprises MAC-CE.

Aspect 24 is the apparatus of any of aspects 1-23, further includes thatthe at least one processor is further configured to switch to the targetrelay as indicated in the relay switch command.

Aspect 25 is the apparatus of any of aspects 1-24, further includes thatthe target relay information is indicated in the relay switch command.

Aspect 26 is the apparatus of any of aspects 1-25, further includes thata base station determines the target relay from the subset of candidaterelays based on the measurement report.

Aspect 27 is the apparatus of any of aspects 1-26, further includes thatthe source relay determines the target relay based on the measurementreport.

Aspect 28 is a method of wireless communication for implementing any ofaspects 1-27.

Aspect 29 is an apparatus for wireless communication including means forimplementing any of aspects 1-27.

Aspect 30 is a computer-readable medium storing computer executablecode, where the code when executed by a processor causes the processorto implement any of aspects 1-27.

Aspect 31 is an apparatus for wireless communication at a source relayincluding at least one processor coupled to a memory and configured totransmit, to a UE, a candidate relay configuration, the candidate relayconfiguration including information of candidate relays and a relaymeasurement configuration; receive, from the UE, a measurement report ofa subset of candidate relays; and transmit, to the UE, a relay switchcommand to switch to a target relay from the subset of candidate relays.

Aspect 32 is the apparatus of aspect 31, further including a transceivercoupled to the at least one processor.

Aspect 33 is the apparatus of any of aspects 31 and 32, further includesthat the at least one processor is further configured to transmit themeasurement report to a base station.

Aspect 34 is the apparatus of any of aspects 31-33, further includesthat the relay measurement configuration comprises an indication of ameasurement gap configuration.

Aspect 35 is the apparatus of any of aspects 31-34, further includesthat the indication of the measurement gap configuration indicateswhether candidate relays are within a bandwidth configured forcommunication between the UE and the source relay.

Aspect 36 is the apparatus of any of aspects 31-35, further includesthat the measurement gap configuration is not provided for referencesignals from candidate relays having a same SCS as the source relay.

Aspect 37 is the apparatus of any of aspects 31-36, further includesthat the reference signals from the candidate relays are within anoperating bandwidth configured for communication between the UE and thesource relay.

Aspect 38 is the apparatus of any of aspects 31-37, further includesthat measurement resources allocated for the candidate relays are withinthe bandwidth configured for communication between the UE and the sourcerelay.

Aspect 39 is the apparatus of any of aspects 31-38, further includesthat the reference signals from the candidate relays have a samenumerology as the source relay.

Aspect 40 is the apparatus of any of aspects 31-39, further includesthat the measurement gap configuration indicates that a measurement gapis utilized for reference signals from candidate relays that are notwithin the bandwidth configured for communication between the UE and thesource relay.

Aspect 41 is the apparatus of any of aspects 31-40, further includesthat the reference signals from the candidate relays are not within anoperating bandwidth configured for communication between the UE and thesource relay.

Aspect 42 is the apparatus of any of aspects 31-41, further includesthat measurement resources allocated for the candidate relays areconfigured to be outside of the bandwidth configured for communicationbetween the UE and the source relay.

Aspect 43 is the apparatus of any of aspects 31-42, further includesthat reference signals from the candidate relays comprise a differentnumerology than the source relay.

Aspect 44 is the apparatus of any of aspects 31-43, further includesthat a numerology used for the measurement gap is based on a numerologyof a physical channel or bandwidth associated with the source relay.

Aspect 45 is the apparatus of any of aspects 31-44, further includesthat a numerology used for the measurement gap is based on a numerologyof a reference channel associated with the candidate relay.

Aspect 46 is the apparatus of any of aspects 31-45, further includesthat the measurement gap is common for reference signals from candidaterelays with a same numerology.

Aspect 47 is the apparatus of any of aspects 31-46, further includesthat a base station determines a list of candidates relays for thecandidate relay configuration.

Aspect 48 is the apparatus of any of aspects 31-47, further includesthat the at least one processor is further configured to receive, fromthe base station, the candidate relay configuration.

Aspect 49 is the apparatus of any of aspects 31-48, further includesthat the at least one processor is further configured to determine alist of candidate relays for the candidate relay configuration.

Aspect 50 is the apparatus of any of aspects 31-49, further includesthat the measurement report comprises a measurement of a Layer-1 RSRP ofthe source relay and the subset of candidate relays.

Aspect 51 is the apparatus of any of aspects 31-50, further includesthat the measurement report is carried over PSCCH or PSSCH.

Aspect 52, the method of any of Example 31-51, further includes that thesubset of candidate relays is provided to the UE in the candidate relayconfiguration.

Aspect 53 is the apparatus of any of aspects 31-52, further includesthat the at least one processor is further configured to receive, from abase station, the relay switch command.

Aspect 54 is the apparatus of any of aspects 31-53, further includesthat the relay switch command is transmitted to the UE via Layer-1 orLayer-2 signaling.

Aspect 55 is the apparatus of any of aspects 31-54, further includesthat the Layer-1 signaling comprises control information or sidelinkcontrol information.

Aspect 56 is the apparatus of any of aspects 31-55, further includesthat the Layer-2 signaling comprises MAC-CE.

Aspect 57 is the apparatus of any of aspects 31-56, further includesthat the target relay information is indicated in the relay switchcommand.

Aspect 58 is the apparatus of any of aspects 31-57, further includesthat the at least one processor is further configured to transmit, to abase station, the measurement report received from the UE; and receive,from the base station, an indication of a target relay from the subsetof candidate relays.

Aspect 59 is the apparatus of any of aspects 31-58, further includesthat the base station determines the target relay from the subset ofcandidate relays based on the measurement report.

Aspect 60 is the apparatus of any of aspects 31-59, further includesthat the source relay determines the target relay based on themeasurement report.

Aspect 61 is the apparatus of any of aspects 31-60, further includesthat the source relay comprises a UE.

Aspect 62 is the apparatus of any of aspects 31-61, further includesthat the source relay comprises a base station.

Aspect 63 is a method of wireless communication for implementing any ofaspects 31-62.

Aspect 64 is an apparatus for wireless communication including means forimplementing any of aspects 31-62.

Aspect 65 is a computer-readable medium storing computer executablecode, where the code when executed by a processor causes the processorto implement any of aspects 31-62.

Aspect 66 is an apparatus for wireless communication at a base stationincluding at least one processor coupled to a memory and configured toconfigure a candidate relay configuration including information ofcandidate relays and a relay measurement configuration; transmit, to asource relay, the candidate relay configuration; receive, from thesource relay, a measurement report of reference signals of a subset ofcandidate relays; select a target relay from the subset of candidaterelays based on the measurement report; and transmit, to the sourcerelay, a relay switch command for a UE to switch to the target relay.

Aspect 67 is the apparatus of aspect 66, further including a transceivercoupled to the at least one processor.

Aspect 68 is the apparatus of any of aspects 66 and 67, further includesthat the relay measurement configuration comprises an indication of ameasurement gap configuration.

Aspect 69 is the apparatus of any of aspects 66-68, further includesthat the indication of the measurement gap configuration indicateswhether candidate relays are within a bandwidth configured forcommunication between the UE and the source relay.

Aspect 70 is the apparatus of any of aspects 66-69 further includes thatthe measurement gap configuration indicates that a measurement gap isnot utilized for reference signals from candidate relays having a sameSCS as the source relay.

Aspect 71 is the apparatus of any of aspects 66-70 further includes thatthe reference signals from the candidate relays are within an operatingbandwidth configured for communication between the UE and the sourcerelay.

Aspect 72 is the apparatus of any of aspects 66-71 further includes thatmeasurement resources allocated for the candidate relays are within thebandwidth configured for communication between the UE and the sourcerelay.

Aspect 73 is the apparatus of any of aspects 66-72 further includes thatthe reference signals from the candidate relays have a same numerologyas the source relay.

Aspect 74 is the apparatus of any of aspects 66-73 further includes thatthe measurement gap configuration indicates that a measurement gap isutilized for reference signals from candidate relays that are not withinthe bandwidth configured for communication between the UE and the sourcerelay.

Aspect 75 is the apparatus of any of aspects 66-74 further includes thatthe reference signals from the candidate relays are not within anoperating bandwidth configured for communication between the UE and thesource relay.

Aspect 76 is the apparatus of any of aspects 66-75 further includes thatmeasurement resources allocated for the candidate relays are configuredto be outside of the bandwidth configured for communication between theUE and the source relay.

Aspect 77 is the apparatus of any of aspects 66-76 further includes thatreference signals from the candidate relays comprise a differentnumerology than the source relay.

Aspect 78 is the apparatus of any of aspects 66-77 further includes thata numerology used for the measurement gap is based on a numerology of aphysical channel or bandwidth associated with the source relay.

Aspect 79 is the apparatus of any of aspects 66-78 further includes thata numerology used for the measurement gap is based on a numerology of areference channel associated with at least one of the candidate relays.

Aspect 80 is the apparatus of any of aspects 66-79 further includes thatthe measurement gap is common for reference signals from candidaterelays with the same numerology.

Aspect 81 is the apparatus of any of aspects 66-80 further includes thatthe measurement report comprises a measurement of a Layer-1 RSRP of thesource relay and the subset of candidate relays.

Aspect 82 is the apparatus of any of aspects 66-81 further includes thatthe measurement report is carried over PSCCH or PSSCH.

Aspect 83 is the apparatus of any of aspects 66-82 further includes thatthe relay switch command is transmitted via Layer-1 or Layer-2signaling.

Aspect 84 is the apparatus of any of aspects 66-83 further includes thatthe Layer-1 signaling comprises control information or sidelink controlinformation.

Aspect 85 is the apparatus of any of aspects 66-84 further includes thatthe Layer-2 signaling comprises MAC-CE.

Aspect 86 is the apparatus of any of aspects 66-85 further includes thatthe target relay information is indicated in the relay switch command.

Aspect 87 is a method of wireless communication for implementing any ofaspects 66-86.

Aspect 88 is an apparatus for wireless communication including means forimplementing any of aspects 66-86.

Aspect 89 is a computer-readable medium storing computer executablecode, where the code when executed by a processor causes the processorto implement any of aspects 66-86.

1. An apparatus for wireless communication at a user equipment (UE),comprising: a memory; and at least one processor coupled to the memoryand configured to: receive, from a source relay, a candidate relayconfiguration, the candidate relay configuration including informationof candidate relays and a relay measurement configuration; measure areference signal of the source relay and each of the candidate relaysbased on the candidate relay configuration; transmit, to the sourcerelay, a measurement report of the reference signal of a subset ofcandidate relays; establishing a connection with a subset of candidaterelays; and receive, from the source relay, a relay switch command toswitch to a target relay from the subset of candidate relays.
 2. Theapparatus of claim 1, further comprising a transceiver coupled to the atleast one processor.
 3. (canceled)
 4. (canceled)
 5. The apparatus ofclaim 1, wherein the measurement gap configuration is not provided forreference signals from candidate relays having a same sub-carrierspacing (SCS) as the source relay.
 6. The apparatus of claim 1, whereinthe measurement gap configuration indicates that a measurement gap isutilized for reference signals from candidate relays that are not withinthe bandwidth configured for communication between the UE and the sourcerelay.
 7. The apparatus of claim 6, wherein the at least one processoris further configured to: tune away from the bandwidth configured forcommunication between the UE and the source relay to measure a referencesignal from at least one candidate relay that is not within thebandwidth configured for communication between the UE and the sourcerelay.
 8. The apparatus of claim 6, wherein the measurement gap iscommon for reference signals from candidate relays with a samenumerology.
 9. The apparatus of claim 1, wherein the at least oneprocessor is further configured to: switch to the target relay asindicated in the relay switch command.
 10. An apparatus for wirelesscommunication at a source relay, comprising: a memory; and at least oneprocessor coupled to the memory and configured to: transmit, to a userequipment (UE), a candidate relay configuration, the candidate relayconfiguration including information of candidate relays and a relaymeasurement configuration; receive, from the UE, a measurement report ofa subset of candidate relays; and transmit, to the UE, a relay switchcommand to switch to a target relay from the subset of candidate relays.11. The apparatus of claim 10, further comprising a transceiver coupledto the at least one processor.
 12. The apparatus of claim 10, whereinthe at least one processor is further configured to: transmit themeasurement report to a base station.
 13. (canceled)
 14. (canceled) 15.The apparatus of claim 10, wherein the measurement gap configuration isnot provided for reference signals from candidate relays having a samesub-carrier spacing (SCS) as the source relay.
 16. The apparatus ofclaim 10, wherein the measurement gap configuration indicates that ameasurement gap is utilized for reference signals from candidate relaysthat are not within the bandwidth configured for communication betweenthe UE and the source relay.
 17. The apparatus of claim 10, wherein theat least one processor is further configured to: receive, from a basestation, the candidate relay configuration, wherein the base stationdetermines a list of candidates relays for the candidate relayconfiguration.
 18. The apparatus of claim 10, wherein the at least oneprocessor is further configured to: determine a list of candidate relaysfor the candidate relay configuration.
 19. The apparatus of claim 10,wherein the at least one processor is further configured to: receive,from a base station, the relay switch command.
 20. The apparatus ofclaim 10, wherein the at least one processor is further configured to:transmit, to a base station, the measurement report received from theUE; and receive, from the base station, an indication of a target relayfrom the subset of candidate relays.
 21. An apparatus for wirelesscommunication at a base station, comprising: a memory; and at least oneprocessor coupled to the memory and configured to: configure a candidaterelay configuration including information of candidate relays and arelay measurement configuration; transmit, to a source relay, thecandidate relay configuration; receive, from the source relay, ameasurement report of reference signals of a subset of candidate relays;select a target relay from the subset of candidate relays based on themeasurement report; and transmit, to the source relay, a relay switchcommand for a user equipment (UE) to switch to the target relay.
 22. Theapparatus of claim 21, further comprising a transceiver coupled to theat least one processor.
 23. (canceled)
 24. (canceled)
 25. The apparatusof claim 21, wherein the measurement gap configuration indicates that ameasurement gap is not utilized for reference signals from candidaterelays having a same sub-carrier spacing (SCS) as the source relay. 26.The apparatus of claim 21, wherein the measurement gap configurationindicates that a measurement gap is utilized for reference signals fromcandidate relays that are not within the bandwidth configured forcommunication between the UE and the source relay.
 27. The apparatus ofclaim 26, wherein a numerology used for the measurement gap is based ona numerology of a physical channel or bandwidth associated with thesource relay.
 28. The apparatus of claim 26, wherein a numerology usedfor the measurement gap is based on a numerology of a reference channelassociated with at least one of the candidate relays.
 29. The apparatusof claim 26, wherein the measurement gap is common for reference signalsfrom candidate relays with a same numerology.
 30. A method of wirelesscommunication at a user equipment (UE), comprising: receiving, from asource relay, a candidate relay configuration, the candidate relayconfiguration including information of candidate relays and a relaymeasurement configuration; measuring a reference signal of the sourcerelay and each of the candidate relays based on the candidate relayconfiguration; transmitting, to the source relay, a measurement reportof the reference signal of a subset of candidate relays; establishing aconnection with a subset of candidate relays; and receiving, from thesource relay, a relay switch command to switch to a target relay fromthe subset of candidate relays.
 31. The method of claim 30, wherein themeasurement gap configuration is not provided for reference signals fromcandidate relays having a same sub-carrier spacing (SCS) as the sourcerelay.
 32. The method of claim 30, wherein the measurement gapconfiguration indicates that a measurement gap is utilized for referencesignals from candidate relays that are not within the bandwidthconfigured for communication between the UE and the source relay. 33.The method of claim 32, further comprising: tuning away from thebandwidth configured for communication between the UE and source relayto measure a reference signal from at least one candidate relay that isnot within the bandwidth configured for communication between the UE andthe source relay.
 34. The method of claim 32, wherein the measurementgap is common for reference signals from candidate relays with a samenumerology.
 35. The method of claim 30, further comprising: switching tothe target relay as indicated in the relay switch command.
 36. Themethod of claim 30, wherein the target relay information is indicated inthe relay switch command.